Darren Sharper received a nine-year prison sentence after pleading guilty to sexual assault charges.

The ex-NFL player faces further time in jail in three other states where he is also charged with drugging and raping women.

He will serve about nine years in federal prison as part of an agreement to resolve all nine rape charges against him in Los Angeles, Las Vegas, New Orleans and Tempe, Arizona.

The deal includes a 20-year prison term in California, but because of legal stipulations and credit for time already served, Sharper will serve "a little less than nine years of actual custody time," his attorney, Blair Berk, said in court on Monday.

The former defensive back was suspected of a number of serial rapes which ended in January 2014, when he was arrested on a suspicion of rape in Los Angeles. At the time of his first arrest, he had 20 zolpidem tablets in his possession – a sleeping drug also known as Ambien.

He obtained a prescription for the drug after suffering insomnia, as the result of his 14-year career in the NFL with the New Orleans Saints, Green Bay Packers and Minnesota Vikings, according to a workers compensation claim form he filed in 2012.

According to court records, the drug could be added to drinks rendering women unconscious and then making it possible for them to be raped. This is what authorities say Sharper did again and again, according to court records.

Sharper was charged with nine rapes in four states, including three in consecutive nights in two different states in January 2014.

In Los Angeles, he was charged with drugging and raping two women – one in October 2013 and one in January 2014, according to USA Today. In the first one, Sharper met two women at a club in West Hollywood and later asked them to his hotel room, where he offered them a drink, according to a police report of the incident filed in court.

"Within minutes of consuming the beverage, both girls reported to have blacked out," the report states. Several hours later, one woman woke up naked with Sharper sexually assaulting her.

By agreeing to the plea deal, Sharper avoids the risk of receiving a harsher punishment in the future. For prosecutors, the plea deal avoids the risk of going to trial, where juries might be influenced by Sharper's fame and celebrity.