Watching Pete's life has been like monitoring the progress of a runaway train on a canyon slope.

Somehow, this man has lost control of his life and he looks more like a confused, battered child than a strong, handsome man in his mid-40s.His problem is alcohol, but he has lots of related problems pushing in on him from all sides. He is homeless. He is hungry. He is unhealthy. He is probably mentally ill.

Despite all that, he's always had a certain class, an air of quiet optimism.

When I saw him last week, he was without hope.

Pete lives in the parks of Salt Lake City. Only when the weather is particularly cold and vicious will he venture into the shelters. He takes work where and if he can find it. He gets most of his meals from soup kitchens.

Because of his alcoholism, he is an example of the worst problems that plague some of the homeless and make them unwelcomed by and frightening to the general populace.

When we first met, Pete was disheveled. Not exactly dirty, but rumpled. It wasn't just his clothing that had a slept-in look. Even his skin had it.

He was reserved, not talking to anyone he hadn't known for a while, with the exception of my sister, Kathy. He talked to her a lot. If he hadn't, I probably would never have noticed him. He was just one of many men who seemed to have run low on luck and ambition.

Last winter, he fell and hit his head. We learned later that he was taken to Veterans Administration Medical Center for treatment. When the hospital released him, he was a different man.

This scrubbed, debonair and very attractive man showed up under the viaduct. I looked at him several times before I realized it was Pete. His hair was cut, his clothing was clean and pressed. He could have stepped out of any business office in the city.

The biggest change was in his face. His eyes were clear and clever and he smiled alot.

"I'm working," he said, "and I'm saving my money to go home. I haven't seen my family for years, but I finally called them and I'm going home."

He never gave details, but he'd told Kathy that his parents live in Massachusetts. He has a 19-year-old daughter he tries to keep in touch with. Calling home after so long, he said, was the hardest - and most joyful - thing he'd ever done.

"I do have people of my own," he said.

This bright, new Pete continued for several months. Then the money he had been saving was stolen. After that, he gradually started drifting back, subtly at first. He was sober and clean, but not totally coherent.

"I get the feeling he's mentally ill, though certainly not dangerous" Kathy told me. "When I talked to him (after he started drifting again), he was sober, but he wasn't quite in touch with reality. I hate it, because of all the men who eat under the underpass, he may have the most potential. He talks like he's educated. He can be so attractive and interesting. When he's okay, he is presentable anywhere."

We can only guess what happened to him, based on a pattern that is fairly common with the approximately one-third of the homeless who are mentally ill.

We know that the hospital sobered him up. Most likely, doctors put Pete on medication to control his mental illness. That's an educated guess, because for several weeks there was no trace of the mildly confused air that had always surrounded Pete, drunk or sober.

Unfortunately, one of the most common problems that doctors and social workers encounter with the mentally ill is a tendency for that person, who is feeling clear and healthy and happy, to decide he's okay and no longer needs medication. Maybe some stop because of the cost, I don't know. But I do know that the slide back down the hill is so subtle that most don't know it is happening until they crash to the bottom, out of control.

I am haunted by the Pete I saw last week. There was nothing subtle in the devastation of his life. His hair sprouted out in every direction, his eyes were red-rimmed and haunted. His hands trembled. He could hardly speak.

But the frightened-looking man-child did manage to say, apologetically and repetitiously, "I don't want a drink. I need a drink. I'm dying."

I think he probably is. And I'm not sure who or what can get this lonely man out of the gully and back on the peak.

I just hope someone can find a way to hit the brakes and bring him safely home.