Heart failure caused the death of the second chimpanzee from Ohio State to die after being moved to a Texas animal sanctuary.
The 16-year-old male, named Bobby, was found dead in his enclosure last month.
An examination of the body showed the chimpanzee's heart tissue was decaying and indicated he apparently had an existing heart problem.
Bobby was one of nine chimps moved to Primarily Primates in San Antonio after Ohio State decided to close the center where the animals were taught basic counting and letters because of a lack of funds.
In March, a 35-year-old male named Kermit died of a heart attack a day after arriving at the sanctuary.
An animal rights group has filed a lawsuit claiming the chimpanzees are not properly cared for at the sanctuary.