A US court on Thursday, 4 January, sentenced a 78-year-old man to five years in prison for raping his step granddaughter, who had posted a Snapchat video of herself being raped.

James D Allen was arrested in August 2016 after a friend of the 20-year-old victim saw the assault video and informed the police about it. A judge in Ottawa County Common Pleas Court also ordered the grandfather to register himself as a sex offender every 90 days for life.

If Allen is released from jail on parole, he would be bound by the five years of post-release control, the USA Today reported.

The sentencing of the elderly man came after he pleaded guilty to first-degree felony rape charge in October. He had also given alcohol to the victim, which made her incapable of giving consent.

Allen told the court that he was so intoxicated that he did not know what had happened until his attorney showed him the video. He also said that he was not aware at the time that the attack was being recorded.

"Once I was shown the video by my attorney, I realized that it was completely true. At that point, I took full responsibility for my actions and I still do. There's no doubt in my mind that I committed a crime against (the victim) and there's no justification for it," he told the court on Thursday.

The Danbury Township Police Department said that when they initially went for the welfare check after a Texas man requested for it, they found the woman was intoxicated but appeared fine. Officers did not see anything out of the ordinary and thought the woman was safe.

But, the victim's friend called the police again, telling them that he had received two Snapchat videos from his friend that show her being attacked. It was this tip that led to Allen's arrest.

Ottawa County Prosecutor James VanEerten said at the time that it was not clear why the victim made the video, but suggested that she did so to create a record. "It's obviously horrific, but at least it allowed us to put a stop to the situation and make a quick arrest in this case," he added.

Police chief Michael Meisler had earlier said that the most upsetting thing about this case was that "this is her step grandfather". "He married her biological grandmother. He was the one who provided her with the alcohol that evening."