SAN FRANCISCO (AP) – The elderly Texas billionaire who married Anna Nicole Smith in the last year of his life never intended to leave the former stripper any portion of his vast fortune, a federal appeals court ruled on Friday.

The 9th US Circuit Court of Appeals sided with a Houston jury that said J. Howard Marshall was mentally fit and under no undue pressure when he wrote a will leaving nearly all of his $1.6 billion estate to his son E. Pierce Marshall and nothing to Smith.

The ruling was the latest development in the bitter 15-year legal battle. Smith said the elder Marshall promised her more than $300 million, even though there was no written documentation.

The fight between Smith and E. Pierce Marshall started in a sleepy Houston probate court and stretched all the way to the US Supreme Court while outliving its two combatants.

It may reach the high court again.

Kent Richland, a lawyer for Smith's estate vowed to appeal the latest ruling, possibly to the Supreme Court on different issues than those it first considered. "It really is a unique decision," Richland said. "We have to take it farther."

Pierce's widow and two sons said they hoped the legal battle was close to ending.

"Our only wish would be that Pierce were here to see his vindication," the family said in a prepared statement.

The decision – if it holds up – is bad news for Smith's ex-boyfriend Larry Birkhead and their three-year-old daughter Dannielynn. The child was named Smith's heir in 2008 after she died of a drug overdose at 39 at a Florida hotel.

Birkhead and attorney Howard K. Stern were placed in charge of Smith's estate.

Stern and two other people have pleaded not guilty to charges of conspiring to provide thousands of prescription pills to the former model before her death.

The convoluted dispute over J. Howard Marshall's money has its roots in a Houston strip club where he met Smith. The two were wed in 1994 when he was 89 and she 26. Marshall died the next year and his will left his estate to his son.

Smith challenged the will in a Houston probate court, alleging the billionaire's son illegally coerced his father to exclude the former Playboy model from sharing the estate.