BATON ROUGE -- Two men shot to death while working on a house in old South Baton Rouge in 2017, and a man thought to have witnessed that crime and killed a few hours later all may have been – to varying degrees – victims of a complex, murderous drug-trafficking operation.

Arrest warrants describe “an extremely violent group of large-scale narcotics traffickers” pulling the strings and paying hit men in cash and heroin to eliminate potential problems.

Investigators from local and federal agencies have been pursuing the group for “more than a decade,” the warrants said.

On Thursday, police booked Dexter Collins, 39, on first-degree murder in the Sept. 8, 2017 shooting death of David Walker. The 68-year-old was killed hours after police had questioned him in the murders earlier the same day of Donovan Cummings, 49, and Harold Anthony, 36.

Anthony was a friend of Walker’s. The house on Thomas H. Delpit Drive where he and Cummings were working on that morning was next to Walker’s.

Walker told police he didn't see who killed the men. Shortly after that, he was found, dying from gunshot injures, in a car at 3615 Seneca St.

The first arrest in Walker’s death came more than a year later. Terrell Anthony, whose brother was one of the double-murder victims, was booked in October 2018 with second-degree murder in that case. Investigators suggested at the time that Terrell Anthony may have believed that Walker did see the murders and was withholding information from police.

Anthony was released on a $300,000 bond in the Walker murder and required to wear a GPS ankle monitor and observe a nightly curfew.

Almost exactly a year later, Anthony allegedly hid in a woman’s Livingston Parish home, holding a child and nanny hostage and then killed 31-year-old Jessica Clark when she arrived home from a weekend trip. Anthony had been living with Clark for some period of time and the two were romantically involved, investigators said.

Anthony was booked with first-degree murder and with robbery in Clark’s death.

In the Walker case, a witness reported having seen Collins getting paid after the killing and having been told “explicit details” of the crime by people directly involved, according to an arrest warrant.

Collins is also accused of having killed a 32-year-old Port Allen man months before Walker’s death. Lorenzo Dixon was found injured, having been shot in a car at 4149 Winbourne Ave. on April 22, 2017. He died nearly a week later. A witness reported seeing at least two masked gunmen who stood over Dixon and shot him repeatedly as he tried to get away from the car, the warrant said.

Kelvin Lee Phillips, 41, is also accused of being one of the gunmen in the attack on Dixon, according to his arrest warrant. Both he and Collins were booked Thursday on first-degree murder in that crime.