By Drew Singer

STEUBENVILLE, Ohio (Reuters) - Two high school football players from Ohio were found guilty on Sunday of raping a 16-year-old girl at a party last summer while she was in a drunken stupor in a case that gained national exposure through social media.

Ohio authorities also promised on Sunday to continue the investigation to determine if other crimes had been committed.

Trent Mays, 17, and Ma'lik Richmond, 16, two members of Steubenville's "Big Red" football team, were found delinquent in the sexual assault of the girl in the early morning of August 12 when witnesses said she was too drunk to move or speak.

Judge Tom Lipps ordered Richmond held in a juvenile detention facility for at least one year and Mays at least two years. The juvenile system could hold them until age 21. Both were required to register as juvenile sex offenders.

The defendants could be heard sobbing after Lipps announced his decision in the non-jury, juvenile court case. Mays also was found delinquent on a second charge - taking and sending a picture of the girl to other people.

Mays and Richmond apologized to the victim before Lipps imposed detention. Both had denied the charges and said any sex that occurred was consensual.

"I had no intention to do anything like that," said Richmond, who walked up to the girl's mother in the courtroom and apologized to her.

"I forgive you," she replied.

Afterward, the girl's mother said the defendants displayed a lack of human compassion or "any moral code."

"This does not define who my daughter is," she said in a statement. "She will persevere, grow and move on. I have pity for you both. I hope you fear the Lord, repent for your actions and pray hard for forgiveness."

Richmond's attorney, Walter Madison, said Sunday they would appeal the decision.

"This is an invasion of justice at best, a miscarriage of justice at worst," Madison said, adding that Richmond's family was devastated.

Adam Nemann, who represents Mays, left without commenting.

Ohio Attorney General Mike DeWine said the case could not be brought to a "finality" without a grand jury and he was asking the Jefferson County courts to name one in mid-April to determine if other crimes had been committed.

Crimes that might be considered include failure to report a felony, a misdemeanor, and tampering with evidence, he said, adding that there was no limit to what they might be looked at.

"NO STONE UNTURNED"

Investigators interviewed 27 partygoers but 16 others refused to cooperate and numerous witnesses could be called to testify before a grand jury that could meet for a number of days, DeWine told a news conference.

"This community needs assurance that no stone has been left unturned in our search for the truth," DeWine said.

The investigation has included interviews with home owners, the school principal, superintendent and football coaches from Steubenville high school, DeWine said.

Bob Fitzsimmons, an attorney representing the girl, said on Sunday his side still was weighing whether to file a civil lawsuit.

The case drew national attention to the town, 40 miles west of Pittsburgh, after a photo and video from the party that appeared to document the assault were posted online.

The computer hacking group Anonymous publicized the picture of two males carrying the girl by her wrists and ankles and organized protests accusing the town known for its "Big Red" football team of covering up the involvement of more players.

Three teammates of Mays and Richmond were granted immunity and testified against them at the trial. DeWine said Sunday the immunity granted to those players under the specific circumstances would carry over to the grand jury.

The trial's testimony was capped by the girl's acknowledgment that she had little memory from that night.

Lipps said the evidence presented was profane and ugly at times and said that alcohol consumption showed a particular danger to "our teenage youth."

Prosecutors had argued that the things that made the girl an imperfect witness, her substantial impairment, also made her a perfect victim.

Under its policy of keeping the names of accusers in rape cases confidential, Reuters has not identified the girl.

(Writing by James B. Kelleher and David Bailey; Editing by Steve Gorman, Xavier Briand and Bill Trott)