CHICAGO (CBS) — An indictment was expected Thursday in the fatal shooting of a 7-Eleven clerk during a January robbery in northwest Indiana.

Police and federal prosecutors said they know who shot 60-year-old Roger Unton on Jan. 20. Around 4:30 a.m., a man walked into the 7-Eleven at 6031 Hohman Ave. in Hammond and announced a robbery. Police said the suspect shot Unton when the robber became enraged after seeing Unton press the store’s panic button.

The store’s surveillance camera recorded the robbery, including a close-up of the suspect, who was wearing a wig and mask.

Investigators said they have caught the man they earlier described as “an animalistic predator who clearly has no value for human life.”

After the slaying, 7-Eleven offered a $10,000 reward for information leading to the killer’s arrest, but Unton’s niece appealed for information by appealing to the sense of compassion of any possible witnesses.

“It shouldn’t be about the reward money. It should be about the family that has to suffer without him,” Rebecca Van Auken said.

It’s unclear if a tip from the public led to the arrest. Police and prosecutors were set to announce an indictment of Union’s killer Thursday morning.

Prosecutors said they also would discuss their efforts to fight armed robberies in the entire northwest Indiana area.