(NewsNation) — The manhunt for a most wanted criminal is over, in large part thanks to the victim’s mother.

Until this week, Ray McLeod had the highest reward ever posted to the the U.S. Marshals Service’s top 15 list: $50,000.

McLeod and Krystal Mitchell dated for a few weeks in 2016. They went out one night in Southern California and she was later found dead, strangled to death in a condo where the couple had been staying.

Her family was devastated by the news.

Police say McLeod, a former Marine, then took off to Mexico, and was considered armed and dangerous and violent. McLeod not only was wanted for murder but he had a history of domestic abuse, as well. He was spotted from time to time in Mexico, Guatemala and Belize, but the trail was basically cold.

Josephine Wentzel, Mitchell’s mom, then began working on the most important case of her life, her daughter’s murder.

“I had to go through a mother’s nightmare,” Wentzel said.

She dug in, flooding social media with posts about her daughter and her alleged killer. She worked leads in Mexico and Central America, even placing ads there. Her relentless work netted thousands of leads, which she turned over to a fugitive taskforce … all while raising her daughter’s two young children.

“I just pray that that … I would see him in prison so that my kids will know … that I did everything possible to bring justice for their mom,” Wentzel said.

In the end, a tip came in that a disguised McLeod was teaching English to adults in El Salvador.

“It’s not like this guy could just hide. … I mean, you got a Marine big bodybuilder type all tatted up and everything else and you just don’t manage (to disappear like that), especially (in) the South American countries,” former Homeland Security agent Robert Allen said.

Wentzel said she cried when she heard the news, after a six-year emotional journey.

“To know that I put all those hours and all that time away from life itself, you know, from my own family, searching for him … it was such a tremendous accomplishment,” Wentzel added.

U.S. marshals traveled to El Salvador to help local authorities arrest McLeod. He was extradited and brought back to San Diego this week. He faces murder, attempted murder and fleeing prosecution charges.

If convicted, he faces 25 years to life.