(CNN) -- A West Virginia lawman known for cracking down on drugs will be buried Sunday.
Walter E. "Eugene" Crum was gunned down while eating lunch in his squad car on Wednesday.
His daughter said "it's a strong possibility" the Mingo County sheriff was killed for vigorously pursuing the illicit trade.
Crum had taken office only three months prior to his killing but already had built a reputation for taking out dealers and shutting down "pill mills."
"My dad fought tirelessly against drug abuse. He just wanted to clean up the county and make it a better place to live," Crum's daughter, Julie Hall, told CNN's Fredricka Whitfield on Saturday in her first television interview since her father was killed.
"Things are still under investigation at this time. We really are unsure," Hall said.
Loved far and wide
A line of Mingo County residents who came to view Crum's body stretched out into the parking lot of the local high school Saturday evening, CNN affiliate WSAZ reported.
Deputies drove up with Crum's widow, Rosie Crum, who is now sheriff, in the late afternoon.
Fire and sheriff's department vehicles blocked off streets. Officers from various divisions across the state and from South Carolina lined the entrance to the school. They stood in unison sequence, their hands clasped in front of them, their heads bowed and their eyes gazing at the ground.
Suspect in custody
Investigators have not publicly identified a possible motive in the case, but they have a suspect.
Tennis Melvin Maynard, 37, is being treated at an area hospital after one of Crum's deputies wounded him, authorities said.
A witness saw the sheriff's shooting and called 911, giving police a license plate number and description of the car, the Mingo County sheriff's office has said.
According to investigators, when deputies spotted Maynard, he led them on a high-speed chase before crashing his SUV. When he got out of his damaged vehicle, he pulled a gun, they said.
Authorities have questioned Maynard twice, including shortly after he was shot. They will not disclose what he said the first time, and they said he was too medicated to give a lucid statement the second time, Williamson Police Chief Dave Rockel said.
A search of Mingo County court records shows no criminal arrests or civil cases involving Maynard. His only citation involves failure to wear a seat belt, according to the records.
Maynard's mother, Olgie, said her son spent time in a state hospital for mental health issues in recent years.
"He went crazy," she said, explaining that her son hadn't been the same since he was involved in a workplace explosion five or six years ago in Alabama. "He was out in the yard yelling. We called the police, and they took him away."
Since then, she said, Tennis had gotten more psychiatric help at another mental health center. At home in Ragland, where he lives with his parents, he mostly stayed in his bedroom and watched television.
"He talks a lot to himself," she said. "He was never violent."
The Bureau of Alcohol, Tobacco, Firearms and Explosives has traced the gun that authorities say was used in the shooting of Crum, according to West Virginia State Police.
But police have refused to release the results of the trace at this time or say whether the gun was purchased by the suspect.
Crum made a name for himself within West Virginia law enforcement circles for his Operation Zero Tolerance, the anti-drug enforcement policy that he put into place shortly after taking office in January.
Crum's wife, Rosie, was appointed Thursday to finish the remainder of her husband's term, with an election set for 2014.
"She was the one who knew him best and knew what he wanted to accomplish," Hall said.
Hall said she and her brother were concerned for their mother's safety in the wake of the shooting but believe she is the best person to carry on their father's legacy.
CNN's Susan Candiotti, Carol Cratty, Ross Levitt and Greg Botelho contributed to this report.