He would comb the streets and shopping centers of Prince George's County, dressed in his out-of-fashion black suit, skinny tie and sneakers, handing out gospel tracts and talking about Jesus.

He was looking, he used to say, for lost souls, and so it was perhaps inevitable that Herb Tappan, a college-educated scientist who had turned increasingly to God, found Wondel Smith, a homeless teenager with a history of bad luck and violence.

In Wondel Smith, Tappan found a perfect lost soul -- a young man, he told friends, he desperately wanted to help but wasn't sure he could. In Tappan, Smith for the first time in his life met an adult who seemed to care.

For a while the two seemed to connect, but in the end, their friendships, like a bad chemical reaction, blew violently and fatally apart. On the afternoon of July 12, Herb Tappan was found dead in his Suitland home with a knife wound in his chest. A few days later, Wondel Smith, 18, was arrested and charged with his murder.

To friends and work associates, Tappan's violent death at 43 was shocking but in some idefinable way almost predestined. His religious fervor had driven him in the last few years to seek out those on the edge of society, its outcasts and misfits, for whom violence is frequently a way of life.

To those who had found Tappan's transition to an evanglical Christian perplexing, his death gave them few answers. For those who shared his new-found religious zeal, Herb Tappan died as he lived, trying to serve God.

"He tried to live like Jesus," said one church associate. When he discovered hours after he was killed, Tappan's friends say he looked peaceful, as if he had been praying.

Throughout his life, Herb Tappan remained an enigmatic figure and most of his friends and coworkers know only bits and pieces of his story. Even his two brothers and one sister know little about their youngest brother who left their Rutland, Vt., hometown in 1955 to attend Colgate University.

Single, a loner, aloof from family and friends, Herb Tappan rarely talked about himself, preferring to draw out other people, and offer his support when they needed it.

He was a fastidious man, friends recall, who shunned caffeine, alcohol, cigaretts, salt and sugar and even medicine. And almost always, no matter where he was, he wore the same thing: an out-of-date black suit and tie with either sneakers or homemade shoes on his feet.

Even during family get-togethers, he would wear the same unusual outfit, recalled one of his brothers, Eugene, recently. And when the relatives piled into the car for a holiday at the beach, clad in bathing suits and towels, Herb would wander the shoreline in his suit.

"He wanted to be properly dressed at all times," Eugene Tappan said. "He always wore a suit and tie no matter what the occasion even when he was out on a construction job."

Tappan's greatest connection to people seemed to come through religion, his friends and family say. Although raised as a Baptist, he became more devout in recent years and to make fervent expressions of his commitment.

Religion seemed to hold for him what a career never did. Trained as a geologist when openings in the field were few, Tappan came to Washington after military service and found a job with the Navy Oceanographic Office, mapping the ocean floor.

He would go out on ships for a month at a time apparently the solitude and opportunity for contemplation fit his needs.

Surrounded by hundreds of miles of sea, alone with his thoughts and with few connections to people around him, Tappan at this point apparently began to grow increasingly religious.

"He was looking for a family, an association with people," said Eugene Tappan. "Some people go to singles bars or other things and some people do it through the church. What he ended up finding was a very warm, close family-type relationship."

About five years ago, Tappan was introduced by a neighbor to the Evangel Assembly of God Church in Camp Springs, a charismatic evangelical church where the Bible is read literally and faith healing is frequently practiced. He joined the church about two years after that.

The church seemed to bring focus to his changing religious consciousness. He would spend four nights or so a week attending services or prayer groups and other nights he would go out distributing gospel tracts and talking to people about Jesus.

"He always had a box of gospel tracts around. They were in his house, the trunk of his car, the back seat and in his hand," said Jerry Carrick, a friend and church member who accompanied Tappan on many of his nocturnal evangelical efforts to movie theaters and shopping centers.

On other nights, Tappan spent hours at the Upper Marlboro Detention Center or with an organization called Teen Challange offering guidance to teen-agers and others who had been introuble with the law. He would try to encourage them to "let Jesus into their hearts," Carrick said, and explain how he had been able to do so.

Sometimes he would take the youths to dinner or take them to a church service. "Herb had been out with some of the meanest ones," Carrick said. "But he felt that was the risk you're going to go to jail and witness [tell people about] the Lord."

No one is more sure where Tappan first met Wondel Smith. They may have met 10 years ago when, according to Tappan's friends, Tappan moved to Navy Day Drive in Suitland. Smith at the time was living with an aunt and uncle around the corner.

He had gone to live with them when his mother died of tuberculosis. His father had never lived with the family, and Smith's two older sisters -- one 16 and one 21 at the time -- lived on their own, according to the younger sister, Barbara Whitaker.

For about two years after his mother died, Wondel Smith lived in a tuberculosis sanitarium where, Whitaker said was kept tied to his crib. When she went to visit him, she was forced to walk him around on a leash.

"After "Dell," as the family called him, went to live with his aunt and uncle he spent most of his childhood in bars with them, Witaker said.

It was a childhood without discipline. Smith ran away several times and never spent more than a few days a year in school after his elementary years, Whitaker said. "He can read words but he dosen't understand what he reads," she said.

"Dell was always on the streets," she said. "He was trying to grow up fast."

In an interview last month at the Prince George's County jail, Smith was asked about his childhood. He said he grew up "on the streets of Suitland," where "all's you gotta know is how to fight and to know the right people."

By 13 he had his first run-in with the law when he was picked up for using drugs, he said. He was ordered to spend some time at Boys Village and it was only the first of many such visits.

The last one, when he was 16, resulted in a period at Crownsville State Hospital for psychological reasons.

By this point, both his aunt and uncle had died and Smith was essentially homeless. He was released from Crownsville and came to stay with his sister Barbara and her family. But mostly, he acknowledges, he roamed the streets.

A strong, lanky 18-year-old, with a loping walk and tatoos on his left arm that he says stand for "war," Smith made money and spent his days hustling drugs on county streets and hanging out with a small motorcycle gang called the Suitland Renegades. During the warm weather he traveled around with the area's small carnivals, running rides and selling tickets.

It was around this time, about two years ago, that Smith's sister Barbara remembered first meeting Herb Tappan. "Dell wanted me to meet him. Dell liked him because Mr. Tappan had taken him all over the place and because he's shown him some compassion.The kid's had it rough all his life and you have to be soft on somebody. You can't show him how mean you can be all the time."

Tappan showed more compassion toward Wondel Smith than the youth had ever before experienced from someone other than his sisters. Tappan took him out to dinner, brought him to a counseling group for teenagers and talked to him about church and God.

Some of Tappan's friends warned him there could be trouble. "Everyone warned him that that boy wasn't right and would hurt him," said Jenny Hill, a self-described born-again Christian who Tappan prayed with regularly.

"But Herb said he wanted to help the boy."

By April of this year, however, Tappan began to have second thoughts about his relationship with Smith, friends said.

He told friends that his house had been vandalized and he felt Smith was responsible. The burgalries continued through spring and Tappan informed county police. They told him, friends said, that they could not do anything until he saw Smith, or any other person, breaking in or stealing from the house.

On June 3, county police swore out a warrent against Smith after a neighbor reported seeing Smith leaving Tappan's house with a wristwatch.

Friends remember Tappan telling them after the warrent was issued that he hoped county police would pick up Smith quickly.

Nine days later, on July 11, Tappan went to church around 8 p.m., according to friends. When the service was over two hours later, Tappan and a group of fellow worshippers went to a pizza parlor in Clinton and stayed there until it closed at midnight. Tappan then drove the few miles back to his one-story home on a quiet street of single-family residences. In all likelihood he arrived there sometime before 1 a.m., friends said.

What happened next, according to police accounts, is that someone -- they believe Smith -- entered the house after tampering with the front door and surprised a sleeping Tappan.

The person then killed Tappan, without a struggle, and stole several objects, including his car.

Smith does not want to discuss the incident although he admits he was there and that he had previously burglarized Tappan's home.

His sister, Barbara Whitaker, said Smith told her that two other friends had entered the house with him and it was one of these two, whose name she didn't know, who stabbed Herb Tappan in an attempt to steal his wallet.

All three then fled, she quoted her brother as saying. County police said they had heard Whitakers's story, but they have closed the case with murder charges entered only against Smith.

Last week a grand jury indicted Smith for murder. Of convicted, he could face the death penalty.