A man who was in the United States illegally allegedly killed a mother of five before fleeing across the border to Mexico, police have said.

Dallas police found the body of Martha Alva, 35, in Northwest Dallas on Sunday morning near a dead end.

Investigators believe her on-again, off-again boyfriend, Ernesto Carrillo Hernandez, killed her.

Hernandez, 32, who was living in Monterrey, did not have legal status in the U.S., according to Fox 4 TV.

Investigators say his car was found near the border in Eagle Pass, Texas.

Alva’s family said she was last seen with Hernandez last Saturday night.

Ernesto Carrillo Hernandez (left), a man who was in the United States illegally, allegedly killed Martha Alva (right), a 35-year-old mother of five before fleeing across the border to Mexico, police have said

Police found Alva's body near the end of Walnut Hill Lane just west of I-35 in Dallas on Sunday morning

Destiny Osorio, 18, is the oldest of Alva’s five children. She will now have to care for the other four.

‘Honestly, I never pictured myself organizing my own mom's funeral,’ she said.

‘This is very tough.’

Osorio says her mother worked at TGI Fridays as a restaurant manager for years.

After work on Saturday night, Hernandez picked Alva up at the TGI Fridays in the West End, her family told investigators.

She was scheduled to show up for work the next day at noon, but she never did.

‘I had a feeling something happened because she never misses work,’ Osorio said.

‘She would put her all into this job. This job was what she lived off of to provide for us.’

Alva’s family said she was last seen with Hernandez last Saturday night. She was picked up by Hernandez after she finished work at a local TGI Friday's. The next day, she did not show up for work

Alva’s family said that Hernandez was abusive toward her in the past, but he was never reported to police

Osorio, who is in college, says she will continue to soldier on because that’s what her mother would have wanted.

‘My mom was strong-minded. She was strong,’ Osorio said.

‘I know if she was here, she would've been like, “Don't let that stop you. You have to continue. You have to do better.”

‘I have to be the role model for my brothers now. I would want them doing the same.

‘I can't let myself go no matter what.’

Alva’s family said that Hernandez was abusive toward her in the past, but he was never reported to police.

Crime Stoppers is offering a $5,000 reward to anyone with information leading to Hernandez’s arrest.

DailyMail.com reached out to Immigration and Customs Enforcement for comment.