On July 30, 1975, Jimmy Hoffa utterly disappeared from the face of the earth.

Born 100 years ago today, Jimmy Hoffa achieved fame as a labor leader, serving as president of the International Brotherhood of Teamsters for more than a dozen years. But “fame” doesn’t quite describe his legacy – maybe the right word is something more like “notoriety.”

Hoffa was accused of being involved with organized crime. He was imprisoned for jury tampering, attempted bribery and fraud. He was pardoned by President Richard Nixon when he was just a third of the way through his 13-year sentence. And, most famously – or most notoriously – he utterly disappeared from the face of the earth on July 30, 1975. Last seen in the parking lot of a Detroit-area restaurant, Hoffa stayed gone and was officially declared dead on the seventh anniversary of his disappearance.

For nearly 40 years since that disappearance, everyone from Detroit-area police to the FBI to countless average-Joe conspiracy theorists has been trying to find Jimmy Hoffa and lay his mystery to rest. Even now, as recently as a few weeks ago, tips continue to surface, leading authorities to search new sites for evidence of Hoffa or his remains.

The most recent Hoffa tip, regarding a field 20 miles outside Detroit, dropped in January 2013. A former crime boss insists that Hoffa’s remains can be found in rural Oakland County – though the tipster claims he’s just sharing information, not responsible for Hoffa’s death.

If previous tips are anything to go on, the authorities will turn up nothing but more disappointment. Another sure-thing tip from four months ago led police to suburban Roseville, Michigan, where Hoffa was said to be buried under a driveway. But extensive testing hasn’t yielded any results.

According to Hoffa’s former driver, the labor leader won’t be found by digging. He’s sure his one-time boss is encased in the concrete of the Renaissance Center in Detroit.

For years, folks have been claiming to know what happened to Jimmy Hoffa, and they’re likely to continue to do so. But each tip ends in another wild goose chase, and Hoffa is still nowhere to be found. For the 100th anniversary of his birth, we offer a wish that the mystery of his disappearance will be solved and his family (and the authorities) will, at last, find closure.