Selena ... Her Murder as Big as JFK Assassination

Selena's murder 20 years ago today was every bit as big as the death of John Lennon, Elvis Presley and the assassination of John F. Kennedy ... so claims the estate of the former Tejano music queen.

Selena's estate claims in new legal docs her record label is hoarding huge amounts of money that should go to Selena's loved ones. In fact, the estate claims Selena actually became way more popular in death than life.

With 60 million albums sold, the estate is livid that UMG is not honoring the deal -- that the estate gets 50% of net profits for things like ringtones, downloads and other stuff.

Selena was gunned down by the former president of her fan club on March 31, 1995.