Anna Kepner's family said they are 'at peace' after her accused killer and stepbrother was finally taken into custody.

Timothy Hudson, 16, was charged with sexually assaulting and killing his 18-year-old stepsister on a Carnival Cruise ship in November.

His pretrial release was revoked on Monday and he surrendered to the US Marshals Service, according to a newly unsealed court order.

The baby-faced defendant will initially be held at the Citrus County Jail in Lecanto, which is authorized to house juveniles, ahead of his September trial.

Shortly after, the Kepner family released a statement to ABC News thanking 'the FBI, the United States Attorney's Office, and the US Marshals Service for their assistance in helping place the accused murderer of Anna Marie Kepner behind bars until trial.'

'It was painful for our family to know that he had been free for as long as he was. We are now at peace knowing that he will not be able to harm anyone else while awaiting trial.' 

The statement, which was signed by Anna's father, Christopher Kepner, and his wife Shauntel Kepner, who is also Hudson's mother, noted Anna's birthday was over the weekend.

'While birthdays are never the same without her, we continue to honor her memory and cherish the love and joy she brought to our lives,' the family said. 

'As we move closer to the start of the trial in the coming months, we remain hopeful for a swift conclusion to this process and for justice to be served.'

Hudson was charged with first-degree murder and aggravated sexual abuse in February but released without bond under the Juvenile Delinquency Act to live with his uncle.

The secretive federal case was finally unsealed in March when Hudson agreed to be tried in US District Court as an adult defendant.

Prosecutors immediately asked Judge Edwin Torres to review his earlier release order because the youngster’s custody arrangements now fall under the much tougher Bail Reform Act.

They argued that Hudson, who is accused of the ‘most serious, egregious, and violative crimes one person can inflict upon another,’ should not be around other kids.

Judge Torres agreed to take the boy into custody but not immediately.

Hudson is set to undergo a mental health evaluation and will be allowed visits from his family and access to the internet to communicate with them, the judge ruled.

‘The murder is alleged to have followed from a brutal sexual assault, and to have been committed against a member of the defendant’s own household in a setting from which the victim could not escape,’ US District Judge Torres wrote in his unsealed order.

‘Indeed, we have two alleged grave crimes here. The forcible sexual assault by itself would be enough to find that release on bond posed too heavy a risk for the community. Had defendant only been charged with that serious offense when he was 18 or older, he would have been likely detained on that basis alone.

‘The level of depravity and psychopathy involved in the commission of that brutal offense would be too hard for most jurists to ignore.’

Hudson was sharing a cabin with his 18-year-old stepsister when she was found raped, strangled and stuffed under a bed aboard the Carnival Horizon in November last year.

Prosecutors have alleged he was 'obsessed' with his stepsibling at the time of the slaying.

'We have evidence he was obsessed with his sister. He had a crush on her,' prosecutor Alejandra Lopez said during a court hearing last month.

This is a developing story.