"My biological clock wakes me at 6am. I shave, put on coffee for my wife and eat some oatmeal, always with a cup of orange juice. When I'm teaching, I wear a coat and tie. But if I'm called out to examine a corpse on a case, it's blue jeans and a sweatshirt — the tie has a tendency to fall down into the volatile fatty acids the human body leaves behind. If you want to find where a body first lay, particularly when it's been scattered by animals, you need to find that stain.

It's interesting what the mind can do. My father shot himself when I was three — I miss him still. And I've lost two wives to cancer. I hate death. I despise funerals. But I never see a forensic case as a dead body. I see it as a challenge to find out who that individual is and what happened to them. Everything I see and smell is a source of data, a possible key to the truth. I feel I am one of the few people who can speak for the dead.

If there's something in the morning paper about a case, I cut it out and put it in a file. I have maybe six file cabinets full of cases. I'm excited by every one — it just isn't every day you find some guy who kills his wife, then carries her round in the back of the car for 10 days before burning her in a trash can. I never had a midlife crisis — there's nothing like a dead body to make my day.

I live 10 miles from the university, and I drive there in a pick-up truck because of all the stuff I have to cart around. Besides, my wife doesn't like me to carry dead bodies in the back of her car. It doesn't matter how many body bags you put around a body, it's still going to leak.

I aim to start on my paperwork at 7.30, before my first class. I'm a hands-on type of person. This morning I showed the students what rodent-gnawing on dry bones looks like. Then we talked about bodies being chewed and scattered by dogs. Dogs take anything they can get a hold of: feet, fingers... Cats prefer lips. The body starts to putrefy within a minute or two of death, and bubbles of gas come up through the mouth. The smell is unbelievably horrible, but cats seem to like it.

An accurate time-since-death estimate can make or break a murder case; that's the reason I created the body farm. I wanted to be able to tell with scientific certainty exactly when a person was killed. We have around three acres, surrounded by a high chain-link fence, and there are bodies all over the ground in varying states of disrepair. They're locked in trunks, in cars, in tanks of water, under concrete, dismembered, burnt, naked and clothed. We study them right from the moment of death until insects have eaten them to the bone. There's a condominium up the hill and in summer, boy, can they smell us. We have four bodies at the body farm hooked up to pipes, and so far we have identified over 400 noxious compounds given off during decomposure.

There are four stages of decay: fresh, bloat, decay and dry. Bacteria start on the inside, blowflies on the outside, converging on a body in their thousands. Nature is extremely efficient at reclaiming us. In Tennessee in high summer, you could go from what you are now to a bare skeleton in only two weeks. Fortunately, bone heals but it always remembers, and it'll tell you almost everything you need to know about a person's life. Recently I was called to testify in the case of a 13-year-old girl who was killed in 1974 and her body thrown into a hay field. The dentist and pathologist are both dead, so I'm the only one who can tally the bones with that case 28 years ago. She had a real nice family and they need closure.

I'm hypoglycaemic, so if I don't eat I really feel bad. I'll get a sandwich or maybe have spaghetti and iced tea with a student. I hate to eat alone. But more than once we've been discussing cases in a restaurant and looked up to find everyone else has moved away.

Often there is a call from the Tennessee Bureau of Investigation during the day, to say they've a case they want me to look at as soon as I can get there. I have a forensic response team, so I'll look to see who's available and take two students. We have coveralls and caps in the truck because crime scenes, particularly burnings, are real dirty.

By six or seven at night, we've gotten all the information we need and we take the remains back to the body farm. I always use paper bags from the grocery store for bones. You put something moist into plastic bags, you get a mould problem. I keep a spare pair of shoes at the body farm. Put it this way: you never know what you're bringing home. The noxious gases putrescine and cadaverine get on your clothes too. You have to get right in the shower and wash your hair and the inside of your nose.

I hate to be late for supper. My first wife, Ann, and I always had supper with the boys no matter what, and we're still a close family. I read a bit, watch the news and I'm always in bed by 10 or 11pm.

I count myself extremely lucky. I have a biological family of three sons, and an academic family of every student I ever taught, and I love them all. I think about my father a lot. I'm in my seventies, yet his death still makes me cry like a child. He's the one man whose death remains elusive. But at the end of the day, I have a feeling of warmth and goodness — I have done what I needed to do. I've heard the faint whispers rising from the dead and I've told their stories."