A man suspected of killing his girlfriend and her teen son at a Georgia home was arrested in Texas while trying to enter Mexico, police said.

William Jerome Adams, 24, was taken into custody in the Lone Star state earlier this week after he tried to enter Mexico after investigators say he gunned down 39-year-old Mary Lindsay and her 16-year-old son, Atif Muhammad, on Friday, Gwinnett County police said.

Adams will be extradited back to Georgia to face two counts each of aggravated assault and felony murder in the double slaying at Lindsay’s home in Flowery Branch, Gwinnett County police spokesman Cpl. Collin Flynn told The Post Thursday.

It’s unclear what law enforcement agency arrested Adams as he tried to get into Mexico, but Flynn said he believed the double murder suspect was stopped by US Border Patrol.

Adams had been in a romantic relationship with Lindsay for just a few months, but it’s unclear what prompted the slayings, Flynn said.

Investigators said they believed Adams fled Lindsay’s home in a black 2010 Audi after the shootings.