A fugitive couple accused of trying to sell their children in Mexico spent the weekend in San Diego jails awaiting extradition to Arizona.

The National Center for Missing and Exploited Children reportedly tipped off federal investigators about the couple. The tip led Mexican authorities to arrest 20-year-old Jessica Heird and 37-year-old Edward Leader in Tijuana on Friday.

Mexican authorities reportedly found the couple's 3-year-old son, but their 18-month-old daughter was still missing.

The San Diego Union-Tribune reported that the boy and girl were sold, though there was no word on who paid for the children or what the price was.

A U.S. Justice Department spokesman said Heird is six months pregnant with the couple's fourth child.

He said authorities recovered three of Leader's other children from a different relationship.