Williams said reportedly the man wasn't feeling well during his crossing and told the others in his group. Some of the men went to seek help while the others stayed with the victim.
The men returned with Border Patrol agents but the victim was already dead.
Williams received a call about the second incident around 8:28 a.m. Thursday.
Williams said Border Patrol agents rounded up a group of undocumented immigrants and while agents were interviewing the immigrants at the Border Patrol sector headquarters in El Centro they were told that one man in their group had became sick and had been left behind.
Agents went to the area where the immigrants said he was last seen. The body of the 27-year-old man was found 120 yards south of the Imperial County marker on Interstate 8. The man's body was about 50 feet down from the highway. His identity also is known but investigators were waiting to notify next of kin before releasing his name.
The Border Patrol's Border Search Trauma and Rescue Unit, or BORSTAR, helped Williams recover the man's body.
Williams praised the unit for its help.
Staff Writer Mario Rentería can be reached at 337-3435.