10/07/2011 04:18 pm ET | Updated Dec 07, 2011

Lettie Fisher, Texas Woman, And Her Mentally Handicapped Son, Missing

Authorities in Texas are trying to locate a missing mother and her mentally disabled son. They have not been seen since they went fishing more than three weeks ago. Investigators now suspect the pair may have met with foul play, police said.

According to the Tyler County Sheriff's Office, 79-year-old Lettie Fisher and her son, 31-year-old John Fisher Jr., have been missing since Sept. 19. The mother and son were last seen leaving Lufkin Memorial Medical Center, where the elder Fisher was treated for breast cancer. After leaving the medical center, detectives believe the Fishers went to their Chester home to pick up their fishing gear and then to Wolf Creek.

"When I came in Monday and they were gone, I thought they were gone to Rayburn, but they never did return Monday night and then I didn't know what to think. I didn't even know where to start looking for them because I don't even know where they fish at on Rayburn," Lettie Fisher's husband, John Fisher, told KTRE News.

John Fisher said it is not uncommon for his wife and their son, who has a prosthetic leg, to go fishing together.

On Sept. 22, Lettie Fisher's 1999 silver Toyota 4Runner was found parked in Magnolia Ridge State Park. According to KPRC, police suspect the vehicle was dumped there by someone else and are investigating the possibility of foul play.

A spokesman for the Polk County Sheriff's Department said authorities have conducted several searches of the park but have yet to find any sign of the couple.

Anyone with more information on the whereabouts of Lettie and John Fisher is asked to contact the sheriff’s department at 409-283-2172.