The family searched the border -- and even the Tijuana morgue -- for 85 days trying to find Pedro, a U.S. citizen unable to explain his plight.
"He was shivering uncontrollably. He could not talk. He could only point," said Mark Rosenbaum of the ACLU.
They are suing federal officials and the L.A. County Sheriff, among others, claiming violations of his constitutional rights.
"Their own records -- sheriff's records, records to which Immigration had access -- said he was born in California," said Rosenbaum. "They apparently never consulted those records."
While Guzman recuperates at home, an Immigration spokesman calls it a one-of-a-kind case, and that Guzman repeatedly told officials that "he was born in Mexico and signed a document agreeing to voluntarily return." In the document, he admits he is in the U.S. illegally.
Yet the sheriff's department's paper trail shows other records -- that Guzman was born in California, and that he had hit his head while in jail and was given psychotropic drugs.
"Their own records said he was hearing voices. No respectable law enforcement officer questions an individual who has been treated like that medically," said Rosenbaum.
Attorneys have another question -- why Guzman was questioned about his nationality in the first place.
"It was purely skin color that he was singled out," said Rosenbaum.
