Time of Death

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Alexander Rodig - One of the best experts on this subject based on the ideXlab platform.

  • Time of Death dependent criteria in vitreous humor accuracy of estimating the Time since Death
    Forensic Science International, 2006
    Co-Authors: Burkhard Madea, Alexander Rodig
    Abstract:

    Abstract Since more than 40 years reports on the rise of potassium concentration [K + ] in vitreous humor have been published with different statements concerning the accuracy of Death Time estimation. In the last years several statistical approaches for a more accurate estimation of the Time since Death have been reported. While in most investigations the PMI has been used as the independent and [K + ] as the dependent variable in linear regression analysis between PMI and [K + ], recently it has been suggested to use [K + ] as the independent variable for regression analysis. Changing the variables would lead to a higher accuracy of Death Time estimation. This has also been recommended for regression analysis between hypoxanthine concentration [Hx] and Time since Death. This hypothesis has been checked on independent cases with potassium and hypoxanthine in vitreous humor. Linear regression with [K + ] or [Hx] as independent variable has revealed a slightly more accurate Death Time estimation compared to a linear regression with PMI as independent variable. Thus, e.g. the accuracy could have been improved from ±25.96 to ± 23.27 h by using [K + ] as independent variable. Another statistical approach has re-evaluated six large studies on the rise of vitreous [K + ] using a local regression analysis (Loess procedure). Based on this re-evaluation an accuracy of Death Time estimation has been recommended (95% limits of confidence of ±1 h in the early PMI and ±10 h, 110 h postmortem) which has surpassed even optimistic results of earlier investigations. This recommended accuracy of Death Time estimation has been checked on a random sample of 492 cases. Only 153 cases have been within the predicted postmortem interval, 339 lay outside with a systematic overestimation of the Time since Death.

  • Time of Death dependent criteria in vitreous humor—Accuracy of estimating the Time since Death
    Forensic Science International, 2006
    Co-Authors: Burkhard Madea, Alexander Rodig
    Abstract:

    Abstract Since more than 40 years reports on the rise of potassium concentration [K + ] in vitreous humor have been published with different statements concerning the accuracy of Death Time estimation. In the last years several statistical approaches for a more accurate estimation of the Time since Death have been reported. While in most investigations the PMI has been used as the independent and [K + ] as the dependent variable in linear regression analysis between PMI and [K + ], recently it has been suggested to use [K + ] as the independent variable for regression analysis. Changing the variables would lead to a higher accuracy of Death Time estimation. This has also been recommended for regression analysis between hypoxanthine concentration [Hx] and Time since Death. This hypothesis has been checked on independent cases with potassium and hypoxanthine in vitreous humor. Linear regression with [K + ] or [Hx] as independent variable has revealed a slightly more accurate Death Time estimation compared to a linear regression with PMI as independent variable. Thus, e.g. the accuracy could have been improved from ±25.96 to ± 23.27 h by using [K + ] as independent variable. Another statistical approach has re-evaluated six large studies on the rise of vitreous [K + ] using a local regression analysis (Loess procedure). Based on this re-evaluation an accuracy of Death Time estimation has been recommended (95% limits of confidence of ±1 h in the early PMI and ±10 h, 110 h postmortem) which has surpassed even optimistic results of earlier investigations. This recommended accuracy of Death Time estimation has been checked on a random sample of 492 cases. Only 153 cases have been within the predicted postmortem interval, 339 lay outside with a systematic overestimation of the Time since Death.

Burkhard Madea - One of the best experts on this subject based on the ideXlab platform.

  • Methods for determining Time of Death.
    Forensic science medicine and pathology, 2016
    Co-Authors: Burkhard Madea
    Abstract:

    Medicolegal Death Time estimation must estimate the Time since Death reliably. Reliability can only be provided empirically by statistical analysis of errors in field studies. Determining the Time since Death requires the calculation of measurable data along a Time-dependent curve back to the starting point. Various methods are used to estimate the Time since Death. The current gold standard for Death Time estimation is a previously established nomogram method based on the two-exponential model of body cooling. Great experimental and practical achievements have been realized using this nomogram method. To reduce the margin of error of the nomogram method, a compound method was developed based on electrical and mechanical excitability of skeletal muscle, pharmacological excitability of the iris, rigor mortis, and postmortem lividity. Further increasing the accuracy of Death Time estimation involves the development of conditional probability distributions for Death Time estimation based on the compound method. Although many studies have evaluated chemical methods of Death Time estimation, such methods play a marginal role in daily forensic practice. However, increased precision of Death Time estimation has recently been achieved by considering various influencing factors (i.e., preexisting diseases, duration of terminal episode, and ambient temperature). Putrefactive changes may be used for Death Time estimation in water-immersed bodies. Furthermore, recently developed technologies, such as H magnetic resonance spectroscopy, can be used to quantitatively study decompositional changes. This review addresses the gold standard method of Death Time estimation in forensic practice and promising technological and scientific developments in the field.

  • Wiley Encyclopedia of Forensic Science - Time of Death Determinations
    Wiley Encyclopedia of Forensic Science, 2009
    Co-Authors: Burkhard Madea
    Abstract:

    Estimation of the Time since Death is a practical task in daily forensic case work. The main principle of determination of the Time since Death is the calculation of a measurable date along a Time–dependent curve back to the start point. Current parameters used for estimating the Time since Death are completely different in nature (physical processes, physical–chemical processes, bacterial processes, and metabolic processes). The methods currently used for estimating the Time since Death and the practical application of different methods are outlined. Keywords: rigor mortis; postmortem lividity; body cooling; nomogram method; gastric content

  • Time of Death dependent criteria in vitreous humor accuracy of estimating the Time since Death
    Forensic Science International, 2006
    Co-Authors: Burkhard Madea, Alexander Rodig
    Abstract:

    Abstract Since more than 40 years reports on the rise of potassium concentration [K + ] in vitreous humor have been published with different statements concerning the accuracy of Death Time estimation. In the last years several statistical approaches for a more accurate estimation of the Time since Death have been reported. While in most investigations the PMI has been used as the independent and [K + ] as the dependent variable in linear regression analysis between PMI and [K + ], recently it has been suggested to use [K + ] as the independent variable for regression analysis. Changing the variables would lead to a higher accuracy of Death Time estimation. This has also been recommended for regression analysis between hypoxanthine concentration [Hx] and Time since Death. This hypothesis has been checked on independent cases with potassium and hypoxanthine in vitreous humor. Linear regression with [K + ] or [Hx] as independent variable has revealed a slightly more accurate Death Time estimation compared to a linear regression with PMI as independent variable. Thus, e.g. the accuracy could have been improved from ±25.96 to ± 23.27 h by using [K + ] as independent variable. Another statistical approach has re-evaluated six large studies on the rise of vitreous [K + ] using a local regression analysis (Loess procedure). Based on this re-evaluation an accuracy of Death Time estimation has been recommended (95% limits of confidence of ±1 h in the early PMI and ±10 h, 110 h postmortem) which has surpassed even optimistic results of earlier investigations. This recommended accuracy of Death Time estimation has been checked on a random sample of 492 cases. Only 153 cases have been within the predicted postmortem interval, 339 lay outside with a systematic overestimation of the Time since Death.

  • Time of Death dependent criteria in vitreous humor—Accuracy of estimating the Time since Death
    Forensic Science International, 2006
    Co-Authors: Burkhard Madea, Alexander Rodig
    Abstract:

    Abstract Since more than 40 years reports on the rise of potassium concentration [K + ] in vitreous humor have been published with different statements concerning the accuracy of Death Time estimation. In the last years several statistical approaches for a more accurate estimation of the Time since Death have been reported. While in most investigations the PMI has been used as the independent and [K + ] as the dependent variable in linear regression analysis between PMI and [K + ], recently it has been suggested to use [K + ] as the independent variable for regression analysis. Changing the variables would lead to a higher accuracy of Death Time estimation. This has also been recommended for regression analysis between hypoxanthine concentration [Hx] and Time since Death. This hypothesis has been checked on independent cases with potassium and hypoxanthine in vitreous humor. Linear regression with [K + ] or [Hx] as independent variable has revealed a slightly more accurate Death Time estimation compared to a linear regression with PMI as independent variable. Thus, e.g. the accuracy could have been improved from ±25.96 to ± 23.27 h by using [K + ] as independent variable. Another statistical approach has re-evaluated six large studies on the rise of vitreous [K + ] using a local regression analysis (Loess procedure). Based on this re-evaluation an accuracy of Death Time estimation has been recommended (95% limits of confidence of ±1 h in the early PMI and ±10 h, 110 h postmortem) which has surpassed even optimistic results of earlier investigations. This recommended accuracy of Death Time estimation has been checked on a random sample of 492 cases. Only 153 cases have been within the predicted postmortem interval, 339 lay outside with a systematic overestimation of the Time since Death.

H Druid - One of the best experts on this subject based on the ideXlab platform.

  • A new model for the estimation of Time of Death from vitreous potassium levels corrected for age and temperature
    Forensic Science International, 2015
    Co-Authors: B Zilg, K Alkass, S Van Den Berg, Samuel Bernard, H Druid
    Abstract:

    Analysis of potassium concentration in the vitreous fluid of the eye is frequently used by forensic pathologists to estimate the postmortem interval (PMI), particularly when other methods commonly used in the early phase of an investigation can no longer be applied. The postmortem rise in vitreous potassium has been recognized for several decades and is readily explained by a diffusion of potassium from surrounding cells into the vitreous fluid. However, there is no consensus regarding the mathematical equation that best describes this increase. The existing models assume a linear increase, but different slopes and starting points have been proposed. In this study, vitreous potassium levels, and a number of factors that may influence these levels, were examined in 462 cases with known postmortem intervals that ranged from 2 hours to 17 days. We found that the postmortem rise in potassium followed a non-linear curve and that decedent age and ambient temperature influenced the variability by 16% and 5%, respectively. A long duration of agony and a high alcohol level at the Time of Death contributed less than 1% variability, and evaluation of additional possible factors revealed no detectable impact on the rise of vitreous potassium. Two equations were subsequently generated, one that represents the best fit of the potassium concentrations alone, and a second that represents potassium concentrations with correction for decedent age and/or ambient temperature. The former was associated with narrow confidence intervals in the early postmortem phase, but the intervals gradually increased with longer PMIs. For the latter equation, the confidence intervals were reduced at all PMIs. Therefore, the model that best describes the observed postmortem rise in vitreous potassium levels includes potassium concentration, decedent age, and ambient temperature. Furthermore, the precision of these equations, particularly for long PMIs, is expected to gradually improve by adjusting the constants as more reference data are added over Time. A web application that facilitates this calculation process and allows for such future modifications has been developed.

B Zilg - One of the best experts on this subject based on the ideXlab platform.

  • A new model for the estimation of Time of Death from vitreous potassium levels corrected for age and temperature
    Forensic Science International, 2015
    Co-Authors: B Zilg, K Alkass, S Van Den Berg, Samuel Bernard, H Druid
    Abstract:

    Analysis of potassium concentration in the vitreous fluid of the eye is frequently used by forensic pathologists to estimate the postmortem interval (PMI), particularly when other methods commonly used in the early phase of an investigation can no longer be applied. The postmortem rise in vitreous potassium has been recognized for several decades and is readily explained by a diffusion of potassium from surrounding cells into the vitreous fluid. However, there is no consensus regarding the mathematical equation that best describes this increase. The existing models assume a linear increase, but different slopes and starting points have been proposed. In this study, vitreous potassium levels, and a number of factors that may influence these levels, were examined in 462 cases with known postmortem intervals that ranged from 2 hours to 17 days. We found that the postmortem rise in potassium followed a non-linear curve and that decedent age and ambient temperature influenced the variability by 16% and 5%, respectively. A long duration of agony and a high alcohol level at the Time of Death contributed less than 1% variability, and evaluation of additional possible factors revealed no detectable impact on the rise of vitreous potassium. Two equations were subsequently generated, one that represents the best fit of the potassium concentrations alone, and a second that represents potassium concentrations with correction for decedent age and/or ambient temperature. The former was associated with narrow confidence intervals in the early postmortem phase, but the intervals gradually increased with longer PMIs. For the latter equation, the confidence intervals were reduced at all PMIs. Therefore, the model that best describes the observed postmortem rise in vitreous potassium levels includes potassium concentration, decedent age, and ambient temperature. Furthermore, the precision of these equations, particularly for long PMIs, is expected to gradually improve by adjusting the constants as more reference data are added over Time. A web application that facilitates this calculation process and allows for such future modifications has been developed.

O. Trujillo - One of the best experts on this subject based on the ideXlab platform.

  • Evaluation of hypostasis using a colorimeter measuring system and its application to assessment of the post-mortem interval (Time of Death)
    Forensic Science International, 1996
    Co-Authors: P. Vanezis, O. Trujillo
    Abstract:

    Hypostasis was measured in 93 cadavers using a tristimulus colorimeter in order to investigate its relationship with the Time of Death. The intensity (lightness) of the hypostasis in each case was measured over a period of 4 h and the rate of change in lightness derived. When examined against the Time of Death, it was found that there was a good correlation between the two. Namely, that the rate of change of lightness (and it can be inferred that this represents displaceability) decreases as the post-mortem period increases. The shift in hypostasis was particularly marked in the first 12 h and decreased thereafter. However, hypostasis could be useful for Time of Death estimation for up to 48 h. After this Time, the degree of change was small or non-existent and by 72 h hypostasis had become fixed in the majority of cases, within our measuring period of 4 h.