News coverage of Erick Alcantar Almanza's arrest in Mexico (KNBC).

Authorities in Mexico caught up to a California man who allegedly tried to smuggle his partner's dead body across the border.

According to reporting by Los Angeles-based NBC affiliate KNBC, 44-year-old Erick Alcantar Almanza is behind bars in Mexico, where he fled after allegedly killing his longtime partner, Aracely Romero. KNBC reported that the couple's oldest son spoke to the station in an interview and said that Almanza allegedly confessed to the murder while on the road to the U.S.-Mexico border, with Romero's dead body next to him in the car's passenger seat.

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Almanza apparently spoke to several members of his family, who said that they last saw Romero on Friday. KNBC reported that Almanza's mother called Mexican authorities, telling them that her son killed Romero, with whom he shared five children between the ages of 16 and 26 years old. Authorities believe that Almanza allegedly killed Romero in Long Beach, California.

Miguel Angel Gaxiola, a prosecutor out of Baja California in Mexico, told KNBC, "Right now, we are exchanging information to try to locate the scene of the crime that occurred there in Long Beach."

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The son who spoke to KNBC told the station that his father had struggled with mental illness for years.

Almanza was arrested on Sunday in connection with Romero's murder. According to KNBC, he told detectives that he and Romero had an argument leading up to the alleged killing. Neither a motive nor a cause of death was made clear.