Martha Martinez believes her sister’s gruesome murder may have been avoided if the United States immigration system wasn’t a complete mess.

Her sister, 27-year-old Angie Martinez, was murdered last July when the mother of three’s repeatedly deported husband slipped back into the U.S. and bludgeoned her with a hammer and strangled her with belt, Texas Tribune reports.

Mexican national Juan Francisco De Luna Vasquez, who had been deported four times, pleaded guilty to murdering his wife earlier this week, and a jury Thursday sentenced him to life in prison, according to the news site.

“The system needs to change,” Martha Martinez said. “Police and Border Patrol need to be more careful with people who have been deported. This could have been prevented. She would still be here.”

The victim’s other sister, Julie Deyver, told KGNS the violence in the couple’s relationship escalated leading up to the July 2015 murder.

“It started with a slap and she had called the cops then it escalated to hitting her,” Deyver said. “She didn’t always call the cops. He would verbally abuse her and physically abuse her.”

Defense attorneys framed the case as a crime of passion, while prosecutors argued it was premeditated.

“In the charge of the court, the jury had to answer ‘no’ to a special issue of punishment which stated that the defendant did not act in the heat of passion arising for adequate cause,” Webb County District Attorney spokeswoman Yanira De Leon said in a statement.

“After two hours of deliberation, the jury assessed the punishment of life in prison.”

Martinez is survived by three children, ages 10, 9 and 4, according to the Tribune.

The Tribune detailed De Luna’s lengthy criminal history, which dates back to 2006:

De Luna was first arrested in January of that year on an assault charge that was later dismissed. He was deported to Mexico later that month.

In late June 2006, he was apprehended by the U.S. Border Patrol and charged with improper entry by an alien, federal court documents show. But days later he was back in Webb County police custody after being picked up and charged with evading arrest, resisting arrest and making terroristic threats. The charges were still pending when Angie Martinez was killed.

On July 3, 2006, a federal magistrate convicted De Luna of improper entry and ordered him deported and placed on unsupervised probation for three years. He paid a $10 fine but didn’t serve prison time.

In 2010, De Luna was arrested after a warrant was issued for failing to show up to court on his earlier charges, according to Webb County Jail records. But he was out on the streets soon after. 

In the fall of 2013, De Luna was arrested and charged with DWI and striking an object on a highway. With his previous charges still pending, he was booked into Webb County Jail again. But he bonded out the same day after posting $2,500.

U.S. Border Patrol refused to confirm De Luna’s history of deportations, citing privacy laws, but records show ICE issued a detainer shortly after he killed his wife, which means De Luna will be transferred into federal custody if and when he ever leaves prison, according to the news site.