ROSCOE, Ill. (CBSDFW.COM/AP) — A quirky Illinois museum is home to what’s believed to be Lee Harvey Oswald’s original tombstone. But how it got there is a bit mysterious and now a Texas club owner is threatening legal action to get it.

Historic Auto Attractions features artifacts related to President John F. Kennedy, including the gravestone of his suspected assassin. The museum is 90 miles from Chicago.

Museum owner Wayne Lensing says he acquired the granite slab over a year ago. But the owner of Poor David’s Pub in Dallas says it’s his.

David Card says Oswald’s mother put it in her Texas home’s crawl space. He claims that after she died his father and stepmother bought the house and a step cousin wrongly sold the tombstone to Lensing.

Card believes it’s worth $100,000.

Oswald is buried in Rose Hill Cemetery in east Fort Worth.  His current tombstone has a mysterious story of its own.

(Copyright 2012 by CBS Local.  The Associated Press contributed to this report.  All Rights Reserved.)