A former East Texas lawman suspected in the shooting death of a DPS trooper struggled with drug addiction before losing his career.

"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," Brandon Wayne Robertson wrote in a 2006 letter to Gregg County District Judge Alvin Khoury. "I fought this battle of addiction for four years."

Apologetic and empathetic themes prevailed throughout Robertson's three-page letter in which he pleaded for probation for a 2004 drug possession charge. Robertson wrote that his bond had been revoked after he missed a court hearing because of car trouble. He asked Khoury to think of his family, health and future.

"I'm ready to begin to put this behind me," Robertson wrote. "I'm sitting in jail not able to provide for my family and (it's) for the miserable part of my life and the mistakes I have made that I have so desperately tried to put this behind me."

Robertson was sentenced to four years in state prison. He served about six months and was paroled just more than a year ago.

Officials with the Kilgore and Overton police departments and Rusk County Sheriff's Office confirmed that Robertson worked for them.

Robertson began his law enforcement career with the Overton Police Department in 1992. He then worked for the Kilgore Police Department from May 1995 to March 1996 and for the Rusk County Sheriff's Office from May to December 1996. Robertson returned to the Overton department in January 1997 and remained there until February 1999. The Texas Commission on Law Enforcement Officer Standards and Education reported that Robertson's license expired in 2001.

Officials at the Overton Police Department declined to comment on Robertson.

His work in Kilgore was unsatisfactory, according to Kilgore Capt. Randy Hancock.

"He was here for about nine months, and he damaged three cars," Hancock said Wednesday, adding that Robertson resigned.

Former Rusk County Sheriff Cecil West said Robertson was a good employee. Robertson left when the department's administration changed.

"When he worked for me he was a lot younger," West said. "He did an excellent job while he was here."

The Kilgore Police Department reported Robertson graduated from Frankston High School in Anderson County.

Robertson was in the Gregg County Jail several times between 2004 and 2006 on charges that included possession of a controlled substance, theft and unlawfully carrying a weapon. He listed a Tyler address when he was arrested in September 2006.