A contributory diagnosis of drowning in putrefactive corpses using the electric impedance spectroscopy

The diagnosis of drowning is incredibly challenging in modern forensic practice after corpses have begun to putrefy. The objective of this study was to develop a method for drowning diagnosis using impedance spectroscopy. Thirty-two adult white rabbits (1.8-2.2kg) were divided into four groups. All rabbits were anesthetized using a mixture of isoflurane and oxygen. One group was drowned into fresh water, while the second one was drowned in salt water; the third group were sacrificed and immersed in fresh water, whereas the last group were sacrificed and then immersed in salt water. All animals were in water until putrefactive changes began to appear, usually limited to 96 hours at The left lung of each rabbit was selected for analysis. Solartron SI1260 impedance analyzer (Solartron) was used in the detection. The maximal value of the real part of impedance (Z^/) in drowning-fresh/salt water group was dramatically lower than in postmortem submersion-group (p<0.01). Compared among the drowning groups, the salt water group showed significantly lower impedance than fresh water group (p<0.01). There were no significant changes in postmortem submersion groups (p>0.05). These data indicate that impedance spectroscopy is a sensitive way to judge the drowning of putrefactive bodies and postmortem submersion both in salt and fresh water.