Murder and Mayhem (33 page)

Can the Coroner Distinguish Between Drug Overdose and Gunshot as the Cause of Death?

Q: Suppose a character is fatally shot (either by another party or by himself—to be determined) after ingesting

twenty-five tranquilizers. How would a medical examiner determine the time lapse between the ingestion of the pills and the gunshot? Could he determine whether the person was conscious and could shoot himself, as opposed to being out cold, which would indicate homicide? What would the M.E. look for? What blood tests or other tests would he run? How quickly can he get results? If this occurred on a Friday night, what is the soonest the autopsy would be done?

A: The time lapse between ingestion and death would be a best guess. The data used by the M.E. in this circumstance would be dissolved versus undissolved pills in the stomach, the presence of other food materials, and the levels of the drug in the blood and urine of the victim. Each drug has a known absorption rate and excretion rate, but this is altered by other foods taken, other drugs involved (either as part of the suicide/murder or medications that the victim takes routinely), the age of the victim, what diseases the victim has (particularly gastrointestinal problems), and a host of other factors. Add to this that everyone is different, and the problem becomes more complex.

Digestion and absorption cease at death, so the stomach, blood, and urine contents and their drug concentrations would be relatively frozen at that time. After analyses of these, the M.E. could make a guess as to when the drug was taken. From the blood levels he could also make a judgment as to the victim's physical and mental abilities. Each drug is different, of course, so the effects of the particular drug used would be taken into account.

I know this is very general, but the problem is complex and multifactorial. In your scenario you could go either way and be okay. The M.E. could reach the conclusion that based on the stomach contents and blood levels, he believed the victim could not have shot himself or he believed the exact opposite. Say the blood levels of the drug were very high, at a level where the victim would

likely be in a coma; the M.E. would state that the death was a homicide. Or if the levels were low, he would state that the victim could have pulled the trigger. Two different stories. The choice is yours since either would work.

The testing of stomach, blood, and urine contents for drugs could be done in a few hours if the drugs involved are common and easily tested. If they are less common and require special testing, the samples may have to go to a more sophisticated lab, and that could take weeks.

The autopsy would probably be done on Monday unless the M.E. requested that it be done sooner; then it could be done anytime.

Can the Coroner Determine the Cause of Death a Month Later?

Q: In my story, a male character is struck in the head with a rock and left in a basement. This occurs during a cold February in a northern climate. The nighttime temperatures are in the 20s, and there is snow on the ground. Several days later the man is found dead, and the body is moved to a remote area. A month later someone finds the body and calls the police.

My questions: Is it more likely that the man was killed by hitting his head on the rock or by later exposure? A month after death, can the coroner or M.E. determine the cause of death and that the body was moved?

A: The cause of death could be the blow to the head, or the victim may merely have been rendered unconscious and then froze to death—death from hypothermia. Though he may never be completely sure, the M.E. would be able to make an educated guess as to whether the blow was powerful enough to cause death. He would look for a fracture of the skull and, more important, signs of bleeding in and around the brain. We call these "intracranial bleeds," which basically is any bleed inside the cranium (skull). Bleeding within the brain itself is called an intracerebral bleed, and bleeding around the brain could be either a subdural or an epidural bleed, depending on exactly where the bleed occurs. Any of these can be deadly, especially if not treated fairly promptly. If the M.E. finds any of these at autopsy, he could reasonably conclude that the blow was the proximate cause of death. If he finds none of these, he might state that the cause of death was due to exposure and hypothermia.

At autopsy there may be no specific findings that indicate death from hypothermia. Alternatively, the characteristic brownish pink discoloration of the skin on the elbows, knees, and, less often, the face and flanks may be seen. The presence of these changes would support a finding that death occurred from freezing.

Since the weather you describe is cold, the body and these findings would likely be well preserved for a month or longer.

Lividity—the purplish discoloration of the skin due to settling of blood in the tissues after death—becomes fixed after six to eight hours. It settles in the dependent or lower areas of the body as dictated by gravity. Once it becomes fixed, moving the body will not result in a shift of the lividity to a newly dependent area. For example, if the victim dies while lying on his back, the lividity would settle along the back and buttocks. If he is rolled to his stomach several hours later, the fixed lividity does not shift but remains where it originally settled. If the lividity pattern doesn't match the body position at the time the corpse is discovered, then the M.E. would conclude that the body had been moved.

Is It Possible to Detect Morphine in a Body Two Months After Death?

Q: A woman kills her husband with IV morphine. She dresses him like a bum and dumps his body in an alley. He has never had dental work and never been fingerprinted. Although the body is found soon after the murder, identification isn't made for two months.

Could the coroner find that the cause of death was morphine after this time period?

A: Yes. Morphine sulfate (MS) would remain in the tissues since all metabolic processes of the body shut down at death. Thus, the MS wouldn't be metabolized (broken down). Blood and tissue samples would likely show its presence.

This is particularly true in the circumstance you describe. Since the body was found soon after the murder, the remains would be well preserved, as would the forensic evidence. An autopsy would likely be performed fairly quickly to determine the cause of the unwitnessed death and to determine if the death was natural or possibly a homicide. The coroner would then store the body in a refrigerated environment until the identification was made.

If the body was found two months after death and was only skeletal remains, the M.E. would have a tougher time finding the MS.

Can a Blood Alcohol Level Be Determined in a "Floater" After Two Weeks?

Q: Is it possible for a body to float to the top in relatively cold water (about 55 degrees) after two weeks? Would it be possible, assuming that two-week period, for an

autopsy to show the level of blood alcohol? Or would the alcohol dissipate?

A: "Floaters" are corpses found floating in a body of water. They present special problems for the M.E. in determining the time of death. Water temperature, of course, has an effect, as do local tides and predators. The general rule regarding decomposition is that one week on dry land equals two weeks for a submerged body.

To become a floater, a body must be in the water long enough for tissue decomposition from bacteria to begin. This process forms gas as a by-product, and the gas collects beneath the skin and in body cavities. Bodies tend to sink and then rise again in several days when the gas forms, adding buoyancy. They thus become floaters.

The M.E. should be able to determine the blood alcohol level since all metabolic processes cease at death. The level would be fairly stable until the body significantly decomposed. In your scenario the cold water would slow this process and preserve the alcohol longer. I think you would be on safe ground after two weeks at 55 degrees to allow your M.E. to make that determination.

How Long Does the Foam Around a Drowning Victim's Mouth Persist?

Q: My protagonist finds a floater out in the ocean. A gaseous foam is found around the victim's nose and mouth. The question is, how long does this foam last? An hour? Two? Also, my victim was shot in the abdomen, but she expired from drowning. The cause of death is not discovered until the autopsy is done. Am I crystal clear on that one?

A: The problem with your scenario is one of timing. A drowning victim may have frothy water coming from her mouth if she is

pulled from the water fairly quickly—I'd guess within an hour or so. After that, perhaps blood-tinged water would leak from the mouth and nose, but it probably wouldn't be frothy since the lungs would have lost all their air and none would be left to "froth." Think ice cream soda; when the fizz is gone, it's just colored liquid. Froth requires air in the lungs, and in a drowning the air is expelled or absorbed into the water, and thus the lungs of someone who has been underwater for several hours are typically waterlogged.

In a floater, the body would have to be in the water for a while— long enough for tissue decomposition from bacteria to begin (see previous question). This process forms gas as a by-product, and the gas collects beneath the skin and in body cavities. Bodies tend to sink and then rise again in several days when the gas forms, adding buoyancy. They thus become floaters. Under these circumstances the hands and feet would swell (after several days), the outer layer of skin would separate from the underlying tissues (five to six days), the skin of the hands and the nails would separate (eight to ten days), the entire body would become swollen, and the tissues would become fragile and be easily damaged during removal from the water. But foaming from the mouth or nose would not be present.

Timing of the floating depends on several factors, including water temperature, currents, the size of the victim, and other variables. For example, a body will float after eight to ten days in warm water and two to three weeks in colder water. Cold slows the process of decomposition by slowing bacterial growth and, thus, gas formation.

So you have to decide which situation is best for you: a recent drowning where the victim is found underwater and dragged up and has foam around the mouth and nose, or a floater who pops up many days after the murder and does not have any foaming.

You are correct that an M.E. could determine the cause of death was drowning as opposed to the gunshot. He could also determine if it was a freshwater or a saltwater drowning. This is complex to explain, but an M.E. can tell the difference. (See the later question, "Can the Coroner Distinguish Between Freshwater and Saltwater Drowning?") This fact was used in the movie
Chinatown.

From How Small a Sample Can DNA Be Obtained?

Q: I know that DNA samples can be obtained from blood, semen, tissue beneath a victim's fingernails, and other sources. My questions are these: How small a sample can be used? Can dried saliva or a strand of hair be used?

A: DNA resides in the nucleus of essentially every cell in the body and is unique to each of us. Notable exceptions are the red blood cells (RBCs) in the blood. Mature RBCs have no nuclei and thus no DNA. White blood cells (WBCs) do. When blood is used for DNA analysis, it is the DNA in WBCs that is tested.

Each person's DNA pattern is decided somewhat randomly at conception by which sperm fertilizes which egg. It is identical in every cell of an individual's body and remains unchanged throughout his or her lifetime. Thus, with the exception of identical twins, no two people have the same pattern. This is why DNA is so useful in determining if a given sample came from a particular person. Quite simply, if a match is made, the material could not have come from anyone else.

To extract DNA from a sample, the material must contain cells, though they do not have to be intact. That is, if you look at the sample under a microscope, there may be no intact cells visible, but DNA remains in the tissue or fluid residue. Thus, decomposed blood, semen, or body tissues can still yield usable samples. Even skeletal remains may have usable DNA in the marrow cavity or in the cells of the bone (osteocytes).

In regard to sample size, the larger, the better, but even traces of

fluids or tissue can yield results. The polymerase chain reaction (PCR) method for DNA testing seems to work best for these small samples.

Saliva contains buccal cells (those that line the inside of the mouth), and the nuclei of these cells provide DNA for testing. Saliva can be gleaned from drinking glasses, bite marks, and postage stamps or envelopes. New techniques using fluorescence spectroscopy can identify very small areas of saliva residue on human skin. Saliva can sometimes be obtained from the face mask worn by an assailant during his attack or robbery. A case reported in
The Journal of Forensic Sciences
in 1999 illustrates how small a sample is needed for testing. The body of a female rape and murder victim was recovered from a river after five and a half hours had elapsed. A bite mark yielded enough saliva for DNA testing.

Hair contains no
cells
and therefore no DNA. But hair follicles do. Cut hair is unlikely to be useful for DNA analysis, but hair pulled from an assailant or shed by the attacker during the assault may be the "smoking gun" needed to convict him. A single hair follicle may provide enough DNA for testing.