Ralph Perez Martinez was watching television with his ex-wife when a news report mentioned a $10,000 reward for information about a Indiana businesswoman found shot to death at the Majestic Star Casino.

"Is that all I'm worth?" he said, according to authorities.

The next day, the ex-wife called police and turned him in for the murder of Mary C. Austgen, 76, in March. Martinez, 57, was charged with murder, robbery and criminal confinement.

Police say video shows Martinez driving up to Austgen's family business in Griffith around 2:40 p.m. on March 28. As Austgen started walking down stairs toward the main door to leave, Martinez grabbed her and she fell, police said.

"The suspect is then observed to have a small silver colored semi-automatic handgun in his right hand and had it pointed at Mary and has the gun over her while she lay on the stairs," police said in an affidavit. "The suspect appeared to be saying something to Mary."

The two went back into the building and come back out about three hours later, police said. Austgen got into the driver's seat of her GMC Yukon Denali and Martinez got into the back seat, behind her, and they drove away. Video at the casino shows the SUV entering the parking garage around 6 p.m. and Martinez walking out about 15 minutes later, police said. He was picked up by a black BMW sedan.

Casino workers found Austgen dead in her SUV early March 29 in a parking garage, police said. She had been shot in the abdomen and two diamond rings were missing from her hands.

On Monday, detectives and the Austgen family made a public plea for help. They released photos of Austgen’s distinctive rings, and her son said there was a $10,000 reward for anyone who could help capture his mother's killer. Police also showed photos from the surveillance video.

"That's not me," Martinez said, according to police. "Lots of people with money get killed."

On Tuesday, the ex-wife called police. She said the photo resembled Martinez, and she remembered seeing a ring in the bedroom that resembled one of the stolen rings.

Also, surveillance video showed the suspect with a red and black bag similar to one Martinez used, police said. The ex-wife said she searched for the bag and found a silver handgun inside, court records said.

Officers executed a search warrant at a home in the 12200 block of Lawndale Avenue in Alsip and Martinez was led away in handcuffs. A search of the house revealed a cell phone that indicated Martinez was in the area of Austgen Electric and Majestic Star Casino on March 28, according to court records.

Police ssaid Martinez had once rented from Austgen. He is scheduled to appear in bond court Friday.

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