A Michigan man accused of murdering his three sons, who have been missing since 2010, made a court appearance on Wednesday.

According to The Daily Telegram, John Skelton participated virtually in a probable cause conference in Lenawee County court. This session, initially set for December 1, pertains to charges of murder against him for the deaths of Andrew, 9, Alexander, 7, and Tanner, 5. The incident is believed to have occurred between November 25 and 26, 2010, though the children’s bodies remain undiscovered.

Prosecutors leveled murder charges against Skelton in November, just weeks before he was due to finish serving a 15-year sentence for the unlawful imprisonment of his sons.

At the time of the boys’ disappearance, their parents, Tanya Zuvers and John Skelton, were going through a divorce. Zuvers, who held sole custody, permitted Skelton to have the boys for Thanksgiving. She was supposed to collect them the following day, but Skelton, after a suicide attempt, allegedly refused to disclose their location.

FBI Special Agent Corey Burras revealed that in the month leading up to their disappearance, John Skelton conducted online searches on topics such as neck-breaking, potassium cyanide, and rat poison.

The FBI agent also alleged that John Skelton addressed Zuvers in a suicide note, stating, “You will hate me.” Burras said he believed the note implied that he killed their sons.

John Skelton appeared virtually at March’s hearing to declare his sons legally dead. He did not provide any information about their whereabouts.

“I’m at a disadvantage. Anything I say isn’t going to make a difference,” he said.

In March, a judge granted Zuvers’ petition to have her three sons declared legally dead. However, the judge ruled there was insufficient evidence proving they were murdered on or about November 26, 2010, or that their father killed them.

A probable cause affidavit from early November stated that state police interviewed John Skelton, but he became uncooperative and refused to disclose his sons’ whereabouts. The document stated that he has been “inconsistent and misleading” for the past 15 years.

John Skelton’s bond was set at 60 million. A preliminary hearing is tentatively scheduled for May.