Iowa City police Lt. Doug Hart said police had investigated the possibility of sexual assault prior to 20-month-old Marcus Balderas’ death, but they now find it unlikely.

"Initial observations led investigators to believe this was possible," he said. "Investigation in the following weeks has determined that this most likely did not occur."

While police say sexual assault probably did not occur, Hart said, officials will continue to investigate a substance consistent with semen found on Marcus’ body during medical examination.

Iowa City police officials could not confirm details in the Department of Human Service’s investigation Sunday, and Johnson County Human Service officials could not be reached for comment as of Sunday night.

Jorge Perez, 20, and Mireya Balderas, 18, are charged with beating Marcus to death in April. Both face Class-B felony charges, punishable of up to 50 years in jail.

According to an Iowa City police press release, a medical examination showed 20-month-old Marcus had broken ribs, bruises on his head, face, stomach, and back, bleeding in his head, and numerous bruises on his head. The final autopsy reported the death as a homicide with blunt-force injuries to the head, the release said.

Hart said three children related to Perez were removed from the home and placed into foster care in June.

Balderas is being held at the Johnson County Jail on a $1 million bond, and Perez is being held on a $2.05 million bond.

Perez and Balderas demanded a speedy trial, and they will face a jury trial Sept. 4 with a pretrial conference set for Aug. 24, according to online court documents.

— by Aly Brown