The 16-year-old stepbrother of Anna Kepner waived his appearance in federal court after being indicted by a grand jury in the teenager’s cruise ship death

Anna Kepner.Credit : Jeffrey Greenberg/Universal Images Group via Getty; Anna Kepner/Instagram

The 16-year-old stepbrother of Anna Kepner will not be appearing in federal court for his arraignment on April 22.

The public defender representing T.H. submitted a filing to the court late Tuesday which said that his client would not be in attendance in court the following morning for his first appearance as an adult, at which time he would have been formally charged with murder and aggravated sexual abuse.

Instead, T.H. affirmed that he had received a copy of the indictment and was entering a plea of not guilty to all charges in a signed waiver of appearance, a copy of which was obtained by PEOPLE.

The decision by T.H. to waive his appearance comes in the wake of a motion filed by the U.S. Attorney’s Office for the Southern District of Florida, asking that the 16-year-old murder suspect be detained pretrial now that he is being tried as an adult.

Anna Kepner.Anna Kepner/Instagram

Because T.H. is being charged as an adult, he now faces the possibility of life in prison should he be found guilty on either charge. If he had been convicted as a minor, he would have been eligible for release at the age of 21.

T.H. was a passenger on the Carnival Cruise Line’s Horizon when prosecutors say he sexually assaulted and intentionally killed his stepsister Anna.

The case is being tried in federal court because Anna, 18, died in international waters as the ship was returning to the United States following a weeklong cruise through the Caribbean.

Anna was last seen on Nov. 6 going into the room she shared with T.H. and her 14-year-old half-brother during the blended family vacation. She was found dead under her bed just before noon the following day.

The mother of T.H., Shauntel Kepner, and Anna’s father, Christopher Kepner, refused to let the teenager remain in their home after arriving back in Florida, and he soon moved in with a family member.

He was released back into the custody of that same family member after making his first court appearance in February, a law enforcement source previously told PEOPLE.

Carnival Horizon.Eva Marie Uzcategui/Bloomberg via Getty

Prosecutors are now trying to change the conditions of T.H.’s pretrial release because he is being tried as an adult.

In a motion filed earlier this month, prosecutors wrote that T.H. is a danger to the community.

His own mother agreed in a statement with her husband after T.H. was released from custody following his first appearance in federal court back in February, when he was charged as a minor.

“At this time, it is deeply painful and disturbing to our family that the person responsible is able to walk freely. This reality adds to our grief and outrage,” wrote Shauntel and Chris on social media.

That statement continued: “It is devastating to know that while we live every day with the loss of our child, the individual responsible has not yet been fully held accountable.”

The public defender representing T.H. pointed out in his own court filing that his client had not violated the conditions of his release and arguing that he poses no threat to public safety.