MONTEREY PARK (CBSLA.com) — Authorities on Wednesday released more details about the man they suspect killed an elderly couple in La Verne last December.

The suspect identified by deputies as 23-year-old Luke Fabela is accused of breaking into the Isoms’ 70-acre hilltop estate and attacking Shirley Isom, 74, and Armie Isom, 89.

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Shirley died Dec. 26 at the crime scene from blunt force trauma, while Armie was stabbed and beaten. He was transported to the hospital, where he later died.

The only property taken, authorities say, was a cellphone.

Lt. Dave Coleman of the Los Angeles County Sheriff’s Department said authorities “have no theories about the motive for the murders at all,” during an afternoon news conference.

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The lieutenant said a DNA swab taken from Fabela was a match for blood at the crime scene in La Verne.

“DNA swabs are taken and put into the system,” Coleman said. “We know that Fabela has done state prison time wherein he would have been tested for DNA and we were able to obtain some samples from the crime scene, which ultimately provided us a link to him.”

Fabela has a criminal record.

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Most recently, he was arrested in January in San Bernardino County on charges of joyriding, vandalism, and petty theft. Fabela was previously arrested in January of 2011 on suspicion of making a criminal threat.