OKLAHOMA CITY -- Oklahoma City Police on Friday said a store clerk did not act in self-defense after allegedly fatally shooting a man who the clerk said robbed the store.

Police arrested Trung Nham Duong, 49, on Friday. They said they expect prosecutors to pursue a charge of first-degree murder in connection with the shooting.

Investigators said they believe Duong fired a 9mm handgun as an alleged thief was attempting to leave the store -- not in self-defense.

Police said around 8:30 p.m. Thursday, a man walked into the store and demanded money. At some point during the hold up, Duong pulled a gun and shot the alleged robber, police said.

Police also questions a customer was also in the store at the time of the shooting.

Police have disclosed a prior arrest for Duong. He was charged in 2002 with assault with a dangerous weapon for firing a shot at a motorist who drove off without paying for a fill-up at the gas station.