PIERRE - A Cherry Creek man pleaded guilty in federal court Friday to two counts of second-degree murder for starting a fire that killed his young brother and sister.

Akeem Rooks, 18, also pleaded guilty to aggravated sexual abuse of a third child.

U.S. District Judge Karen Schreier set sentencing for March 6 in Pierre.

The May 2 fire at Cherry Creek on the Cheyenne River Indian Reservation killed Rooks' 4-year-old sister, Keya Rooks, and her 2-year-old brother, known both as Marvin Evenson and Marvin Rooks. They suffocated in the fire, according to court documents.

A third child, 9, is the victim in the sexual-abuse offense, which occurred on the same day as the fire, according to charges filed by prosecutors.

Akeem Rooks already was under arrest on an earlier charge of arson that endangered human life.

The two murder convictions carry a maximum sentence of life in prison, with a mandatory minimum of 30 years. The sexual abuse offense also carries a sentence of up to life in prison.

In exchange for the guilty pleas to second-degree murder of a child and sexual abuse of a child, federal prosecutors dropped charges of first-degree murder.

Rooks spoke very little at Friday's hearing, answering "guilty" to each charge. He also told the judge he understood the terms of the plea bargain and knew he was giving up his right to a trial.

Details of the offenses are explained in a document that has been sealed by the judge. That document describes the facts that support Rooks' convictions.