HOUSTON – KHOU 11 News has learned ballistics tests confirm the man who killed Harris County Pct. 3 Assistant Chief Deputy Clint Greenwood used the same gun to kill himself.

The weapon was a 9 millimeter pistol, investigators say.

William Kenny purchased it in 2014 and had a legal permit for concealed carry, records show.

Kenny had a long history of rambling complaints against Harris county law enforcement, but it’s still unclear why Greenwood was targeted.

Related: Suspect in Deputy Greenwood's murder committed suicide

Related: Funeral for fallen Deputy Greenwood

Greenwood was killed in Baytown as he arrived to work at the county courthouse there nearly two weeks ago. Kenny killed himself a day later outside Ben Taub Hospital.

Baytown PD says Kenny was tracked down with additional surveillance video initially not released to the public. 

"With the help of businesses in the area, we were able to track our suspect vehicle to a convenience store," said Lt. Dorris. "We were also able to do some investigative work on the vehicle aspect of the case, which led us to identifying a rental car, which led us to Mr. Kenny."

Photos: Suspect in Greenwood murder investigation