Officials at the University Medical Center in Tucson, Ariz., are trying to figure out the identity of a patient who lost his memory after being thrown from a pickup truck four months ago.

Nicknamed "Adobe," the man has been hospitalized since April 27, recovering from a severe brain injury, National Public Radio reported.

Officials say he was riding in the truck with several other men when it flipped over on a southern Arizona road. Four men died, 18 were flown to hospitals and at least 20 others escaped, NPR reported. It’s believed all of the men were illegal immigrants.

As a result of the accident, "Adobe" suffered severe damage to his frontal lobe — the part of the brain controlling higher functions and some long-term memory.

A nurse practitioner told NPR "Adobe" he has been crying and talking about his five kids.

"He's homesick," she said. "He tells the nurses he wants to go home."

The problem is — he doesn’t know where home is.

Click here to see a picture of “Adobe” and to read more on this story from NPR.