That man led agents to the bodies of his wife and another man.
Hayes identified the woman as Socorro Arroyo, a Mexican national. He did not have information on her age or where in Mexico she had lived.
Hayes, who declined to name the man who died because his family had yet to be notified, said the man had resided near Mexico City.
Authorities were unsure of the relationship between the two people who died other than they were traveling together.
In a bit of a twist, Hayes said, the investigation has been affected because the husband has disappeared.
He was taken to El Centro Regional Medical Center for treatment for heat exhaustion. Hayes said the man was in the hospital as of last night, when officials from the Mexican consulate in Calexico visited him.
At some point between that visit and this morning, the man left the hospital. Hayes said he is unsure if the man was discharged or simply left.
The two deaths came a full week after the last reported heat death locally — a woman who died in the Ocotillo area after crossing the border illegally with her children in another group of migrants.
That case came just two days after another woman died while crossing illegally with her children.
There still are several weeks left of extreme summer temperatures and it is likely the death toll will rise.
According to Border Patrol statistics, the two deaths Tuesday means that 81 illegal immigrants have died in the Imperial Valley this federal fiscal year, which ends Sept. 30.
Staff Writer Darren Simon can be reached at 337-4082.