Missouri State Highway Patrol troopers were mourning the death of one of their own Monday and trying to find out who killed Sgt. Carl Dewayne Graham.

Graham, 37, a divorced father of a 4-year-old son, was found shot to death in front of his rural Van Buren home about 5:15 p.m. Sunday. A passer-by saw the body and called the patrol, said Roger Stottlemyre, superintendent of the patrol.

Graham had completed his shift and was still in uniform. Officials believe his death was a homicide. Though Graham was at home at the time of the shooting, the patrol characterized his death as in the line of duty, making him the 24th state trooper to die on the job.

No suspects were in custody. The patrol and several other law enforcement agencies were investigating.

Patrol Sgt. Marty Elmore said troopers were questioning several people and trying to identify any "red flags" from investigations Graham was involved with.

"I think a lot of times when you get into the middle of a thing like this officers try not to let their emotions override the job," Elmore said. "The focus has to be on catching Dewayne's killer."

Graham was born in St. Charles County and graduated from Dexter High School in 1986. He graduated from Southeast Missouri State University in 1990 with a bachelor's degree in criminal justice.

Dr. Michael Brown, director of the criminal justice department at Southeast, said he has known Graham since he was a freshman.

"He was a good, solid student who worked his way through school," Brown said. "He achieved his lifelong career dream of becoming a member of the highway patrol."

Brown said Graham kept in touch with him periodically since he graduated and that he had talked with him just a few months ago.

"I've been doing this so long I remember the best and worst among the students, and he was among the best," Brown said. "He was dependable and a good person. It's a terrible loss. I'm glad I had a chance to know him."

Graham joined the patrol in 1993. He was promoted to corporal in 1999 and became a sergeant in 2002.

The shooting left this town of 850 residents shaken. Float Stream restaurant owner Janet Jackson said she was nervous about the fact a killer was on the loose.

"I never lock my doors, but I went home last night and locked my doors," Jackson said.

Jackson said she had just spoken with Graham hours before the killing as he was leaving her restaurant, where he had lunch with the police chief. The two joked in the parking lot.

Graham always had a ready smile, but was a lawman through and through, Jackson said, recalling his military-like purposeful walk.

"Even if he was in civilian clothes, you knew he was in law enforcement," Jackson said.

Mary Crawford, executive director of the Van Buren Youth and Community Center, where Graham served on the board of directors and volunteered, recalled how he helped hand out food and worked with children in the community.

"He was a very, very nice man, a very upstanding individual -- fair and honest," Crawford said.

Staff writer Linda Redeffer contributed to this report.