SEBRING, Fla. -- Officials arrested a man in Florida accused of murdering his wife in Williamson County 20 years ago.

According to a news release from the Highlands County Sheriff's Office in Sebring, Florida, sheriff's detectives, a Round Rock Police Department detective and an investigator from the Williamson County District Attorney's Office arrested 70-year-old William Foster, who had an outstanding felony murder warrant from a murder 20 years ago.

The Williamson County District Attorney's Office said Thursday that a grand jury indicted Foster in his wife's death on Tuesday.

"We've been praying for it. I don't think any of us ever gave up that it would happen," said Donna's sister, Pamela Stevenson. "I knew from the moment that Bill called me on the night he killed her, I knew that he had done it."

District Attorney Jana Duty said in a statement that she received a letter from one of Donna Foster's friends requesting an investigation into her death, leading investigators to revisit the case.

"It's been such a big hole, and it was so frustrating the prior DA would not press charges," Stevenson said.

The district attorney's office said investigators determined on June 16, 1995, the Fosters were in their hot tub with their next door neighbor Bill Smith and his stepdaughter. The four ate dinner, and after the neighbors left, the Fosters returned to the hot tub around 10:30 p.m. Officials said about an hour later, Foster began banging on Smith's door, saying he found his wife lying face down in the hot tub. Foster called 911 while Smith attempted CPR, officials said.

The district attorney's office said Donna Foster had a very low blood alcohol level and no drugs in her system, but she did have "suspicious injuries" consistent with being held under water.

According to officials, before her death, Donna Foster told her close friends and family that her husband had been taking money out of her bank account without her knowledge and that she was going to divorce him. Officials said she also had in excess $350,000 in life insurance with her husband named as the beneficiary.

Foster was not charged in his wife's death, but Donna Foster's family sued him in civil court for wrongful death and won. Her family was awarded $725,000 in damages.

Officials said Foster recently retired and moved to Highlands County about eight months ago. He is being held in the Highlands County Jail pending extradition to Texas.

Donna's family hopes justice will soon be done.

"However long it takes is how long it takes. We've waited this long," Stevenson said.

According to public records, Foster was previously found guilty on an assault charge in Williamson County in 1991.