LINDEN, Texas (AP) _ The suspect in the fatal shooting of a Department of Public Safety trooper killed himself in East Texas on Thursday as authorities closed in on his location, DPS said.

Brandon Wayne Robertson, 37, was found dead of a self-inflicted gunshot wound in a brushy area off a county road just outside of Linden in Cass County. DPS said that authorities had been tracking him with the help of several calls he made to 911 and calls others made to a tip line.

Robertson, a former police officer, was named in a capital murder warrant in the death of Trooper James Scott Burns, a 39-year-old who was killed Tuesday night after pulling over a car near Lake O' The Pines in East Texas.

DPS spokeswoman Sylvia Jennings said that Robertson called 911 one final time Thursday when he heard a police helicopter circling overhead. "So at that point we knew we were at the right location," she said.

Cass County Sheriff James Estes said investigators found evidence that Robertson and his girlfriend had slept in an abandoned barn just off the county road. He said in a story for Friday's editions of the Longview News-Journal that he didn't know how the couple had chosen the barn.

The barn was down a rough, rutted driveway that led up a hill from the road, the Texarkana Gazette reported in its Friday editions.

Authorities said Burns didn't have a chance to remove his seat belt as he stopped his patrol car, just before getting shot multiple times with a shotgun Tuesday night. A passer-by later used the trooper's radio to call for help.

Robertson was an East Texas police officer for seven years at departments in Rusk County, Overton and Kilgore, according to the Texas Commission on Law Enforcement Standards and Education. He left law enforcement in 1999 and was on parole for a drug possession charge.

Robertson's girlfriend was taken into custody at the barn Thursday. DPS said that criminal charges are pending against her.

Robertson was arrested by Department of Public Safety troopers as recently as April 6, when he was charged in Cherokee County with possession of a controlled substance. He posted a $7,500 bond the next day.

"I have had my share of troubles in the past after becoming addicted to pain medication when I was injured in a vehicle accident that brought an (eight-year) career in law enforcement to an end," Robertson wrote in a letter to a judge in 2006 in which he pleaded for probation for the drug possession charge.

He served about six months of his four-year prison sentence and was paroled in April 2007.

DPS trooper and spokeswoman Sylvia Jennings has said she did not know what prompted the pursuit that ended with Burns' death.

Burns was the 83rd state trooper to die in the line of duty, according to DPS. He is survived by a wife and a 5-month-old daughter.

Funeral services for Burns will be at 2 p.m. Saturday at the First Baptist Church in Linden, with burial at Shiloh Cemetery, nine miles south of Linden. Visitation will be at 6 p.m. Friday at the church.

Linden is 140 miles east of Dallas.