EXCLUSIVE: She Was the Last Person to See Jimmy Hoffa Alive — Investigator Tells Radar The Union Boss Was Kidnapped and Shoved into a Car by a Trio of Mobsters Before His Gruesome Death.

One of the last people to see Jimmy Hoffa alive before he disappeared on July 30, 1975 has told RadarOnline.com she witnessed the Teamsters Union president in the back of a car, surrounded by members of the mafia.

Hoffa vanished, never to be seen again, after a missed lunch appointment on the outskirts of Detroit, Michigan.

It has long been assumed that Hoffa, 62, was the victim of a mafia hit, partly due to organized crime's control of the Teamster union's pension fund, which he disagreed with.

Now an investigator has come forward confirming that's exactly what happened.

According to officials, a mobster named Chuckie O'Brien, who was a friend of Hoffa, along with two mafia underlings picked up the union head at the Red Fox restaurant and drove off with him in the backseat.

David Tubman told RadarOnline.com at the same time, his parents were driving down the same Michigan road.

"(Mom and Dad) happened to be driving by the Red Fox, and a maroon Mercury pulled out suddenly, and that caught my mother's eye," he said.

When the driver passed Kenneth and Frances Tubman, he gave them a once-over. Kenneth recognized the driver as O'Brien, and warned: "Frances! Quit looking. That’s the Mafia. Do you want to end up dead in the Detroit River?"

But that only made David's mom more curious.

"And then she noticed in the backseat, two big men in suits. And they were fighting with something, because one man was holding a leash or a strap, so she thought it was a dog, that they were keeping some kind of big dog down in the back seat because their knees were pushed way into their chest."

Days later, with news of the search for Hoffa gripping the nation, Kenneth saw pictures of O'Brien on the news, and recognized him from the maroon car.

That was when the parents realized the dog was actually Hoffa, struggling for his life. They both kept what they saw a secret for decades, for fear of being killed in retribution.

Years later, when they finally did share their secret with son David, he looked into the disappearance himself, sharing his parents' story in his book Jimmy Hoffa Is Missing-The Gap.

David discovered the maroon car pulled into the parking lot of a banquet hall named The Raleigh House, roughly five miles from the Red Fox, where e a garbage truck was waiting. The Raleigh House had trash pickups every Friday – making a garbage truck's presence the Wednesday Hoffa disappeared suspicious.

David further revealed Hoffa was shoved into the truck, and taken to a nearby Central Sanitation Services outside Detroit.

A former employee at the plant told him Hoffa was brought to the trash site and dumped into a giant bundler – which was used to compress thousands of pounds of garbage into a compact cube to then be taken away.

"Hoffa would have been in that bundle," David told RadarOnline.com, adding that the missing union leader was then "sent out to a paper mill where that bundle was liquified and turned into recycled paper and cardboard."