After a long fight with prostate cancer, actor Dennis Hopper passed away at 74 last Saturday. But the "bitter battle" over his multi-million dollar estate has only "just begun," reports the New York Post. Since January, Hopper had been "desperately" trying to divorce his wife of 14 years, Victoria Duffy, 42. But the marriage dissolution didn't go through before his death, which puts the ownership of Hopper's estate and valuable art collection in question. (Watch an E! News report about Hopper's death.) Some key questions:

What does Duffy claim to be entitled to?
According to the couple's prenuptial agreement, Duffy, who has a 7-year-old daughter with Hopper, stands to receive 25 percent of Hopper's estate, plus an additional $250,000 life-insurance payout. Part of Hopper's wealth is in the form of an art collection, much of which Hopper claims Duffy "stole" during the divorce proceedings.

What kind of art did Hopper own?
Mostly modern art, including a portrait of Hopper by Andy Warhol, and works by Jean-Michel Basquiat and Julian Schnabel, among others. A piece by the British grafitti artist Banksy — a sculpture of a TV stencilled with the words, "In the Future Everyone Will Be Anonymous for 15 Minutes" — is reportedly worth around $220,000. (See Hopper's Banksy piece here.) His entire collection is worth about $1.5 million.

Why are Duffy's claims in question?
The couple's prenup stipulated that Duffy and Hopper must be married and "living together" for the prenup to remain vaild. Duffy continues to live on Hopper's property, but in a separate house. Hopper's three adult children, who are battling Duffy over the estate, contest that this voids the agreement. "Personally I think [Duffy is] going to have a real uphill battle," says Andrew Mayoras, a Detroit-area probate attorney and co-author of Trials & Heirs: Famous Fortune Fights!, as quoted by ABC News. "The judge allowing her to remain on the property is one thing. But it's the interpretation of the prenuptial agreement that is going to govern in probate court."

Sources: NY Post, Telegraph, TMZ, ABC