The Seattle man accused of being involved in the bombing of a fertility clinic in Palm Springs last month was found dead in the Los Angeles federal prison Tuesday … and now we have a better idea how he died.

Federal sources tell TMZ … Daniel Park — who was being housed in the Metropolitan Detention Center downtown — stepped up on a table on an upper tier of the facility and jumped … plummeting to the ground floor.

Prison staff attempted life-saving measures … but authorities said the 32-year-old was declared dead at the hospital later that day. It’s unclear how many stories he fell.

Park was accused of providing 270 pounds of ammonium nitrate to the primary suspect — Guy Edward Bartkus, who authorities say carried out the May 17 car bomb attack. Four people were injured in the explosion — but Bartkus, of Twentynine Palms, California, was the only person killed in the blast.

Bartkus reportedly held “anti-natalist” views, meaning he thought humans need to stop procreating. He is reported to have left behind “anti-pro-life” writings before he allegedly set off the bomb.