A San Antonio woman who was found dead Tuesday inside her home — in what was initially believed to be a random robbery gone bad — was actually murdered by her own son, according to police officials.

Matthew Dempsey, 18, has been charged with capital murder for the alleged killing.

His mom, Mary Dempsey, 53, died after suffering some sort of trauma to the body, cops said.

Police, however, wouldn’t confirm whether she had been stabbed, beaten or shot.

“What we can tell right now is there’s obvious trauma,” said San Antonio PD spokesman Doug Greene in a statement to reporters.

Mary was thought to have died following a break-in at her house in San Antonio’s West Side neighborhood — with one major clue being her missing car — but an investigation later revealed what police believe really happened.

Cops said they responded to her home after getting a call from a relative who believed Mary had been robbed. But officers found no signs forced entry.

Neighbors told the San Antonio Express-News that they heard gunshots Monday night, but said that’s not uncommon.

“If we don’t hear (police) helicopters…it’s unusual,” said resident Johnny Arredondo, who is running for City Council.

Drugs and robberies have allegedly been plaguing the area for years, prompting many to believe that Mary had been robbed at first.

“It’s always been a problem up and down this street,” Arredondo said.

Detectives reportedly did some digging and developed some information on Matthew Dempsey, which prompted them to bring the young man in for questioning. The interview was enough to convince authorities to bring charges against him and he was arrested Tuesday night by San Antonio Police.

Investigators have yet to release a motive for the murder. Cops said Matthew did not live with his mother.

“It’s a heartbreaking story,” Greene said. “To find out that it was the son of the victim involved in this, it’s just kind of hard to process but the evidence shows otherwise and we have to go by the evidence.”