Jill Biden‘s first husband, Bill Stevenson, called cops about a domestic dispute at his Delaware home and was there when authorities pronounced his wife dead … TMZ has learned.

Law enforcement in Delaware tells us Bill is the one who picked up the phone and dialed 911 on Sunday night and was waiting at his Oak Hill home when responding officers arrived.

As we reported … cops found Bill’s wife, 64-year-old Linda Stevenson, unresponsive in the living room and tried life-saving measures before pronouncing her dead at the scene. Dispatch audio from the incident mentions “cardiac arrest.”