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DALLAS (CBSDFW.COM) – A Dallas security guard is in jail charged with the murder of his wife.

Police say David Cortez Thompson, 34 killed Blessing Okereke, 30.

Thompson told police Okereke had come to his job on the 400 S. Zang Blvd. Saturday night, confronting him about infidelity.

Thompson said he had just shot his wife at his work place because she tried to kill him in the lobby of the Oak Cliff Tower.

A police affidavit says Thompson believed his wife was reaching for his pistol, and the two began to struggle. Thompson allegedly drew his weapon and fired. Police say the woman was not carrying a weapon.

Neighbors at the apartment complex on McCallum Boulevard in North Dallas live close enough to hear and even see what goes on next door, and some tell us David Thompson and his wife Blessing Okereke had a long history of domestic problems.

Investigators say Thompson shot and killed his wife after she showed up at Oak Cliff Tower where he was working and accused him of cheating on her. The news came as a shock to neighbors like Cristhian Valenciana.

“He was actually a very quiet guy to be honest with you. Never bothered anybody,” Valenciana said.

Valenciana lives down the hall from Thompson’s apartment. While the murder charge came as a surprise, he says he and his neighbors often heard and saw the couple fighting, sometimes right outside their unit.

“They were actually like going at it. I didn’t know if I should stop it or not ’cause she looked very, very aggressive, and I didn’t want to put my hands on a girl especially if he’s there too, you know and try to break them up,” Valenciana said.

Police say Saturday night Thompson claimed he had to shoot his wife and that he feared for his life when she allegedly reached for his pistol. Legal expert Pete Schulte says that could be a difficult defense.

“She was unarmed. She was his wife. It was a family violence type situation. It probably is going to look like he’s going to have a tough time with that argument,” Schulte said.

But Valenciana insists we can’t really be sure what happened in those final moments.

“If he did it out of, you know just to protecting himself, then I’d believe it ’cause I’ve seen where he had to protect himself more than one time,” Valenciana said.

Investigators say Thompson did call 911 and helped police find himself and his gun. He also agreed to be interrogated. He faces one count of murder and is held on $500,000 bond.

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