HOUSTON -

Charges against a man accused of killing a car dealership manager have been upgraded.

Keith Edward Grimmett, 49, has been charged with murder in Robert Kuentz's death.

Kuentz, 30, was shot at Mac Haik's pre-owned dealership in the 11700 block of the Katy Freeway, between Kirkwood and Dairy Ashford, about 9:30 a.m. Friday, investigators said. He died at Memorial Hermann Hospital on Monday.

Investigators said Kuentz and Grimmett got into an argument on Thursday.

"They discussed his sales numbers," prosecutor Natalie Tise said.

While at work on Friday, Grimmett shot Kuentz in the neck and then left the dealership, police said.

Police said they tracked down Grimmett a few hours after the shooting and arrested him.

Grimmett appeared in court Tuesday and was appointed an attorney.

"I really don't want to discuss how he's doing mentally right now, but I do believe he's struggling," defense attorney Sylvia Escobedo said.

While he was in the back of a police car Friday, Grimmett said, "I tried to sit down and have a man-to-man talk with him and tried to get an understanding, but it went south."

Grimmett said he was unhappy about Thursday's meeting and did not like the way Kuentz had spoken to him.

Flag were lowered to half-staff at the dealership on Tuesday to honor Kuentz.

Grimmett is being held in the Harris County Jail without bond. His next court appearance was scheduled for Jan. 16.