LAFAYETTE - While the motive behind the 2009 shooting of Mark Boutin was never determined, authorities said Boutin often stole drugs from dealers by posing as an undercover police officer, according to testimony Wednesday in the murder trial of the man accused of shooting Boutin.

Opening arguments began Wednesday in 21-year-old Troydell Simmons’ second-degree murder trial.

Investigators say Simmons, of Carencro, shot Boutin, 41, of Carencro, once in the head with a 9 mm handgun during the early morning hours of July 2, 2009.

Boutin’s body was found next to a vehicle in the 700 block of Fado Street. It was the city’s first homicide since 2007 and only the second since 2003.

Dr. Joel Carney, a forensic pathologist who performed Boutin’s autopsy, testified Wednesday that Boutin is believed to have been shot at close range through the right temple.

Carencro Police Capt. Ronnie Richard, the lead investigator in the case, said Lafayette police officers found a gun that was later matched to spent cartridges recovered at the crime scene.

The gun was discovered in Simmons’ possession during a traffic stop in Lafayette about three days after the shooting.

Richard testified that Simmons was also seen in the area on the night of the shooting.

Prompted by questions from the defense, Richard said he learned during the investigation that Boutin had a history of drug use and was known to drive away without paying for drugs.

Officers also found handcuffs and a walkie-talkie at the crime scene, he said.

Prosecutor Pat Magee said a motive for the killing was never established.

Maurice Guski, a private investigator who lives a street over from Fado Street in Carencro, testified that he saw Simmons pushing a bike through a nearby yard on the night of the shooting. He picked Simmons out of a photo lineup at the Carencro Police Department about a month later.

Matthew Washington, a longtime friend of Boutin’s, testified Wednesday that he last saw Boutin on the night of the shooting, just before Boutin left to get crack cocaine.

“He did often pretend to be a police officer and drive off with dealers’ drugs,” Washington said in response to questions by Harold D. Register, Simmons’ lawyer.

The trial resumes Thursday at 8:30 a.m.