The courthouse was evacuated, streets into the city were blocked off and officers held white sheets around the crime scene, Crum's body further shielded by two vehicles.
The shooting occurred within a block of the county courthouse, said Office of Emergency Services head dispatcher Willis Spence. Officials planned a news conference for 6 p.m. in the county in the southwest corner of West Virginia, on the border with Kentucky.
Delegate Harry Keith White, who campaigned with Crum last year, said his friend was shot to death in the same place where he parked his car most days to eat lunch, near the site of a former pharmacy known for illegally distributing pills.
Crum led a drug task force and an initiative called Operation Zero Tolerance, making good on a campaign pledge, White said.
"I think anybody you ask would tell you he was a great guy, always with a positive attitude, always trying to help people," White said. "It's just a sad, sad day for Mingo County and the state of West Virginia."
Crum had resigned his post as a county magistrate before launching his sheriff's campaign as a signal of integrity, preferring to run as a civilian rather than an official, White said. He won the primarily handily and ran unopposed in the general election in the fall.
Crum had been a magistrate for 12 years and had previously served as police chief in Delbarton.
White said Crum was dedicated to improving the community and devoted to his grandchildren and adult children.
"He always had family around him," he said.
After dozens of indictments were issued earlier this year, Prosecutor Michael Sparks issued a press release declaring that Crum "exceeded my highest expectations" and "has provided a game changing boost to our drug enforcement program."
Delegate Justin Marcum, D-Mingo and an assistant county prosecutor, called Crum "a true friend to the county."
"He'll be dearly missed," he said.
Williamson, a town of about 3,200, sits along the Tug Fork River in a part of the state long associated with violence. Mingo and neighboring McDowell County are home to the legendary blood feud between the Hatfield family of West Virginia and the McCoy family of Kentucky, a conflict dating to the Civil War.
Crum's county was dubbed "Bloody Mingo" during the early 20th century mine wars, when unionizing miners battled Baldwin-Felts security agents hired by the coal operators.
In May 1920, after evicting striking miners in Red Jacket, some of the Baldwin-Felts men tried to board a train in nearby Matewan but were confronted by the mayor and the chief of police, Sid Hatfield, a former miner, who had family ties to the Hatfields in the feud.
After a gun battle recreated in the 1987 John Sayles film "Matewan," the mayor, two miners, a bystander and three agents lay dead. Hatfield became a hero but was gunned down on the courthouse steps a year later in Matewan.
Though there is no indication of a direct connection, Crum's killing comes on the heels of a Texas district attorney and his wife being shot to death in their home over the weekend, and officials suspect a white supremacist prison gang. Those killings happened a couple of months after one of the county's assistant district attorneys was killed near his courthouse office.
Colorado's corrections director, Tom Clements, was killed March 19 when he answered the doorbell at his home outside Colorado Springs. Two days later, Evan Spencer Ebel, a white supremacist and former Colorado inmate suspected of shooting Clements, died in a shootout about 100 miles from Kaufman. On Monday, judicial officials acknowledged Ebel was freed four years early because of a paperwork error.
U.S. Attorney Booth Goodwin called Crum's killing "shocking" and said he's spoken to the State Police, which will lead the investigation. He pledged the assistance of his office and whatever other federal agencies are needed.
Over the last century, 14 prosecutors have been killed, according to news reports and statistics kept by the National District Attorneys Association. At least eight of them were targeted in the line of duty. At least several were slain in incidents unrelated to their jobs, apparently random acts of violence.
The Officer Down Memorial Page says 197 police officers in West Virginia have died in the line of duty, 136 of them from deliberate gunfire.
Associated Press writers Lawrence Messina in Charleston and Vicki Smith in Morgantown contributed to this report.
Copyright 2013 The Associated Press.