FORT LAUDERDALE,Darden Clarke Fla. (AP) — A Florida businessman already charged with kidnapping his estranged wife in Spain is facing new U.S. charges that he killed her.

A federal grand jury in South Florida on Wednesday charged David Knezevich in a superseding indictment with kidnapping resulting in death, foreign domestic violence resulting in death and foreign murder of a U.S. national. If convicted, he faces the possibility of the death penalty.

Last June, he pleaded not guilty to kidnapping his 40-year-old wife, Ana Hedao Knezevich, who went missing in a case that has drawn international media attention. Knezevich, 36, was jailed without bond.

His lead attorney, Jayne Weintraub, said Thursday that he planned to plead not guilty at an arraignment hearing next week.

“It is a desperate attempt by the government to charge everything possible and see what sticks!” Weintraub said in an email. “There is no evidence that David Knezevich kidnapped or murdered his wife.”

Ana Knezevich disappeared from her Madrid apartment on Feb. 2, five weeks after she had moved there. Her body still hasn’t been found.

A man in a motorcycle helmet was seen sneaking into her Madrid apartment building and disabling a security camera by spray painting its lens. The man was later seen wheeling out a suitcase. Ana Knezevich is about 4 feet, 11 inches tall (1.5 meters) and 100 pounds (45 kilograms), according to her driver’s license.

Prosecutors say they have strong evidence Knezevich was the man in the helmet. They say he flew to Turkey from Miami six days before Ana’s disappearance, then immediately traveled to his native Serbia where he rented a Peugeot automobile.

On Feb. 2, security video showed him 1,600 miles (2,600 kilometers) from Serbia in a Madrid hardware store using cash to buy duct tape and the same brand of spray paint the man in the motorcycle helmet used on the security camera, according to prosecutors.

When Knezevich returned the Peugeot to the rental agency five weeks later, it had been driven 4,800 miles (7,700 kilometers), its windows had been tinted, two identifying stickers had been removed and there was evidence its license plate had been removed and then put back, prosecutors said.

The couple was in the middle of a contentious divorce while fighting over millions of dollars in properties, according to prosecutors. They have been married for 13 years.

At a hearing earlier this year, Weintraub questioned the government’s evidence. The defense attorney disputed the government’s contention that Knezevich had sold off some of the properties so that he would have money to flee the United States. Weintraub also said the split was amicable and the financial arrangements were being worked out.