A Mexican jail warden fell to his death while spying on a couple during their conjugal visit.

Raul Zarate Diaz came crashing down next to a Nicaraguan prisoner and his wife while they were having sex.

Apparently he tripped on a skylight overlooking the conjugal visits section, La Cronica newspaper and InfoRed radio said.

According to local law enforcement sources the warden had with him binoculars and a pornographic magazine.

An official answering the phone at the prison said that police were investigating but refused to provide further details.

The prisoner who was interrupted attempted to start a riot, but the intent was squelched by prison security, the newspaper said.