NEW ORLEANS — (CNN) A man suspected of fatally shooting a Louisiana police officer Wednesday night already was wanted on a charge of second-degree murder, Shreveport police said Thursday.

Grover Cannon is suspected of shooting and killing Shreveport police Officer Thomas LaValley on Wednesday night after LaValley responded to a call at a home in the area, Chief Willie Shaw said Thursday.

“He is nothing to me but a coward who would shoot an officer and hide and run,” Shaw said Thursday, referring to Cannon. “No matter what rock he crawls under, we will find him.”

Police already were looking for Cannon in connection with a different killing, Shaw said. Details of the previous case weren’t immediately available.

LaValley was responding to a call about a potential prowler at an area home. The suspect was initially believed to be in the home, armed and threatening to harm people, police spokesman Marcus Hines said.

After LaValley confronted Cannon, Cannon shot the officer multiple times, Shaw said.

LaValley was taken to a hospital, where he was pronounced dead.

Now, besides the previous charge, Cannon is wanted on suspicion of first-degree murder, Shaw said.

The officer’s death is the 20th this year at the hands of violent suspects in the United States.

Over the weekend, a police officer in Memphis, Tennessee, was shot and killed during a regular traffic stop.

Officer Sean Bolton saw an illegally parked car, pulled up in front of it and shined his spotlight.

When he approached the vehicle, a passenger confronted him.

A struggle ensued, and the passenger shot Bolton multiple times, authorities said.

The car drove off, leaving the officer for dead.

On Monday, suspect Tremaine Wilbourn surrendered to authorities.

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