The case that I've been involved with that took the longest, from murder to conviction, was the Medgar Evers case. Medgar Evers was a civil rights leader, who was assassinated - shot from behind - in 1963,about four months before President Kennedy was murdered. It took 30 years, and an exhumation of the remains 28 years after death, to gather enough evidence to go to trial and convict the shooter.

But I should point out that we medical examiners aren't in the business of solving the murder to get the perpetrator. Our role in solving the murder is to determine what happened, not who done it. I think it was clearly established in 1963 that Medgar Evers was murdered by a single rifle bullet from behind. It took 30 years to get further information that led to the conviction of Byron De La Beckwith.

The most frustrating case that I've been involved with, and that hasn't been solved yet, has to do with poisoning deaths in a hospital more than ten years ago. I'm satisfied from the autopsy findings that a number of persons who died in this hospital were poisoned, but because toxicology has not been able to demonstrate which poison was used, the case remains open. But the paraffin blocks from which microscopic slides are made, and in which tissue is fixed, are kept by hospitals for years. And today, we can find poisons that couldn't be detected 10 or 20 years ago. So with new technologies in the field of toxocologic examination, this case - and others that have languished - may be solved.

Now, in the quickest cases - usually the great majority of murder cases - the medical examiner is able to determine the cause of death at the time of the autopsy, as well as whether it's a homicide, suicide, or accident. This goes for the great majority of murders because when there's a shooting, stabbing, or baseball bat injury, etc., when we do an autopsy, we can find the blood and the holes in the skin, and that leads to a rapid solving of the cause of death. That can be done within a few hours. The longest cases, in general, are the poisoning cases; those are the ones that are hardest to identify because it may take weeks or months to find the poison.

Is it possible for a man's blood DNA to differ from that of his sperm?

No, it's not possible for the DNA in the sperm to have any portions that didn't come from the nuclear DNA in the man's body.

Does it really happen that people shoot themselves with shotguns by pulling the trigger with their toes?

Yes, people can shoot themselves by using a toe or an object, such as a broomstick handle or rolled-up newspaper, to depress the trigger of a firearm. It depends on how the individual sets up the relationship of the shotgun to the part of the body he's intending to shoot. Women rarely use shotguns to kill themselves, but toes or extensions of the hand have been used to reach the trigger if the arms are not long enough to reach it.

Do you think there should be international standards for forensic pathology? For example, in formulae for determining time of death, methods of performing autopsies, how tests are performed, etc.?

I think there should be an attempt to get international standards so that all forensic pathologists proceed in a similar manner in a given type of investigation. Around the world, the standard autopsy is performed typically the same way in the United States, Russia, China and Malaysia. It would be good to standardize the procedures for evaluating a crime scene and the collection of trace evidence. That's something that depends on how meticulous the individual investigator is and what kind of relationship exists between the medical examiner and the police department.

Currently, this varies from jurisdiction to jurisdiction. In 50 percent of United States jurisdictions, the person in charge of the medico/legal aspect of an investigation isn't even required to be a physician. And in most Medical Examiner systems, even when the person in charge is required to be a physician, most M.E.'s aren't forensic pathologists, which is a specific type of physician with special expertise. So, while uniform standards might be hard to establish, it's important that the crime scene be investigated properly, with a search for trace evidence; a proper autopsy has to be conducted, with proper toxicology tests. Those steps could be developed into international standards, just as hospital-conducted, non-forensic autopsy procedures have been standardized.

In a previous Q&A, you wrote that rigor mortis peaks in about 12 hours after death and then recedes. But I've observed human and animal corpses that have remained stiff as long as several days after death. How is that possible?

First, there is a certain normal variation, even though the stiffening of the body, in most persons, comes in 12 hours, remains for 12 hours and goes away in 12 hours. There are exceptions. Sometimes a person has been vigorously exercising or struggling with somebody. The added muscular activity causes rigor mortis to set in more quickly. At other times, hot climate conditions or body fat infiltrating the muscles in heavy people will cause delay of rigor mortis. This is because rigor mortis is a condition that affects muscles, and the more fat you have in the muscles, the less quickly rigor mortis sets in. But the most common cause for prolonged rigor mortis is cold. For example, when a body - human or animal - is found dead in the snow, rigor mortis sets in and remains for many days - or weeks, even - until the snow thaws. And when bodies are brought to mortuaries or to morgues with rigor mortis already present, and then are kept at about 38 degrees Fahrenheit, (to prevent bacteria from growing and causing post-mortem decomposition) that low temperature causes the rigor mortis to stay longer. The colder the temperature, the longer the rigor mortis stays.

In cases presumed to be physician-assisted suicide, how can you tell whether the death was truly a suicide and not homicide? Are there any telltale clues to look for at autopsy?

There are a number of questions that come up with the issue of physician-assisted suicide. Most of the time, such deaths are caused by overmedication, with morphine or other drugs that can cause rapid loss of consciousness and death. One of the issues that comes up, especially concerning people who had been very ill, is whether that person could have obtained and self-administered the drug. But whether or not the physician or somebody administered the medication, whether the decedent took it unassisted,whether or not the medication is given because the decedent wished it, or it was done because it was convenient for other people - these are issues you can't resolve by conducting an autopsy. And you can't tell from the toxicology, either. That's why it's so difficult to decide whether physician-assisted suicide should be permitted here as it is in some European countries - because it's not possible from an autopsy alone to determine whether the decedent really wanted to die.

I've been involved with cases where there's been an issue of whether a death was a homicide or not, where morphine was given in large doses to people who were in coma. We give morphine to diminish pain, but it also depresses the ability to breathe, so that the individual dies faster. And that's the trade-off: less pain, shorter life. But if you're in coma, you don't need morphine to kill your pain, because you're not feeling any pain. We once had a situation where people were dying in a facility right after their medical benefits ran out. And it turned out the individuals were getting morphine they didn't need - because they were in a coma. So, that's one of the situations that medical examiners have to on the alert for, the giving of morphine - especially as our population gets older and more people go into nursing homes and chronic care facilities.

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