From the National Post, re: John Diefenbaker, Prime Minister of Canada 1957-63:

The bizarre reason John Diefenbaker is entombed in concrete: He was afraid enemies would steal his corpse

There’s only one definite way to figure out if John Diefenbaker really did father illegitimate children; dig him up, extract a DNA sample and perform a paternity test.

It’s unlikely that any judge would allow the exhumation of an official National Historic Person. But there’s another, more technical, barrier at play: John Diefenbaker cannot be exhumed.

After the 13th Prime Minister was consigned to the earth on August 22, 1979, the coffins of he and his wife Olive were then covered over with a healthy layer of wet cement — at least according to one account of his life and well-choreographed funeral.

In the 1995 book Trumpets and Drums, Diefenbaker associate Dick Spencer wrote that “the final service rendered Dief by Saskatoon funeral attendants was the pouring of wet cement into his grave, around and onto the casket below.”

Spencer’s description remains one of the only surviving accounts of the unusual measure.

The reason, according to the book, was that Diefenbaker was worried about having his body stolen. Specifically, he had been spooked by an 1876 criminal plot to steal Abraham Lincoln’s body that was foiled at the last minute by an undercover Secret Service agent.

After that, Honest Abe was interred in a steel cage encased by concrete.

“What many weren’t aware of was the Chief’s fascination with Abraham Lincoln’s rites,” wrote Spencer.

“Lincoln had been so protected in his final resting place. Dief requested, and was given, the same precaution.”

More at the link.