There has been no word from 26-year-old Aubrey Moran or her boyfriend, 28-year-old Jonathan Reynoso, since Wednesday night.
On Friday, police found their 2010 GMC Terrain abandoned on the side of the 10 Freeway in Beaumont, but say there were no signs of forced entry or foul play.
Investigators and loved ones are turning to the public for help.
"If there's any missing gaps that we need to fill, please cooperate and bring it further to us so we can do something about it. Please don't be so afraid that you can't come by and help us solve this," said Reynoso's mother, Mayra Torres.
Torres said bloodhounds apparently tracked her son's scent 50 feet into a field then lost it.
Police also say there has been no sign of activity on their cellphones or bank accounts.
"If you have them, let them go. Let them be free. Let them come home. There's people waiting for them. If they're hurt, if it's already been done, then let us know," Torres said.