PHOENIX (AP) -- Former NFL All-Pro safety Darren Sharper was sentenced to nine years in federal prison Monday immediately after he pleaded guilty to sexually assaulting a woman in Arizona, marking the first change of plea of the day for the former safety accused of drugging and assaulting women in four states.

Sharper on Monday admitted to charges of sexual assault and attempted sexual assault arising from the 2013 Arizona case. It is very unusual to sentence defendants immediately after a guilty plea, which normally takes weeks or months.

Sharper and appeared in the Phoenix courtroom by video-conferencing from Los Angeles. He also is expected to change his plea in person in Los Angeles on similar allegations. Similar hearings will follow in Las Vegas this week and in New Orleans in the next month.

NEW ORLEANS - OCTOBER 31, 2010: Darren Sharper #42 of the New Orleans Saints celebrates a play against the Pittsburgh Steelers at the Louisiana Superdome on October 31, 2010 in New Orleans, Louisiana.
Credit Matthew Sharpe/Getty Images

In each state, he's accused of drugging and sexually assaulting women when they were unconscious or otherwise unable to resist or consent.

Maricopa County Superior Court Judge Warren Granville said Sharper will serve his time in federal custody and that the Louisiana case will be resolved through a federal court.

In Arizona, Sharper admitted sexually assaulting one victim, though police say he drugged and sexually assaulted three women, at an apartment in the Phoenix suburb of Tempe in November.

Authorities say a search of the Tempe apartment turned up a shot glass with a white residue that turned out to be zolpidem, and California investigators discovered that Sharper had a prescription for the drug.

Last year, Sharper's attorneys said their client did not make the drinks that authorities say he used to drug the women.

One of the women told police she hadn't had any alcohol that night until Sharper insisted she drink a shot. Another young woman said she had been drugged, then went to bed, locked her door and wasn't attacked.

The next day, one of the women confronted Sharper, who denied wrongdoing, according to the reports.

The reports said Sharper was in Arizona to visit a woman who lived at the apartment. The two had met about a year earlier in Las Vegas.