AUSTIN, Texas — An arrest has been made in the murder of an Austin defense attorney. 

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On Wednesday, the Travis County Sheriff's Office charged Justin Nickolas Twyne with the murder of 74-year-old James Short.

He was detained in New Orleans on unrelated charges.

According to the affidavit, Short went shopping with Twyne at an Austin Walmart the day before the murder.

On Friday, Short texted Twyne and gave him his home address. Authorities say their relationship and the motive are still unknown.

Security footage obtained by the Travis County Sheriff's Office on Friday. At a press conference on Wednesday, the sheriff's office confirmed that additional footage shows James Short shopping with the suspect. 

"The investigation will still continue for the next couple of weeks. That will be our part of the investigation from this point forward is trying to figure out motive," said Craig Smith, of the Travis County Sheriff's Office.

Twyne remains in jail in Louisiana awaiting extradition to Travis County. He has a warrant for his arrest out of Georgia, but not for a violent crime.

Investigators said Twyne's fingerprints matched those found on evidence at the crime scene, including a bloody knife.

Authorities are working to figure out his connections to Austin and New Orleans.