"We cannot come to a unanimous consensus on any of the counts," said the jury's note to Judge Steven O'Neill in Norristown, Pennsylvania. Jurors began discussing the charges late on Monday and worked 12-hour days on both Tuesday and Wednesday.
In response, O'Neill gave a standard instruction that the jurors should continue trying to reach a verdict without compromising any of their individual beliefs.
As reporters streamed out of the courtroom, poet and author Jewel Allison - one of the dozens of women who have accused Cosby of assaulting them - burst into tears. Several accusers have been in court all week awaiting a verdict.
Cosby, the 79-year-old entertainer once beloved for his brand of family-friendly comedy, is accused of drugging and sexually assaulting Temple University administrator Andrea Constand, then 31, at his home near Philadelphia in 2004.
Constand and other accusers say Cosby, the star of the 1980s hit TV comedy "The Cosby Show," often plied them with pills and alcohol before assaulting them, in a series of incidents over four decades.
Constand's allegations are the only ones to result in criminal charges, with many of the others too old to allow for prosecution. Cosby has denied every claim, saying his encounters with Constand and others were consensual.
A hung jury would be a clear victory for Cosby, who would avoid what could have been years in prison for three counts of aggravated indecent assault.
On hearing of the jury's note, his lawyers moved for a mistrial. But O'Neill denied that request as premature.
The jurors have spent days wrestling with which version of the night in question was accurate: Constand's or Cosby's. They have spent days asking to have testimony read back, including Constand's trial testimony as well as the first report she made to police in 2005.
The jury also revisited Cosby's description of the night from sworn depositions he gave in 2005 and 2006 during a civil lawsuit by Constand and a police interview he conducted in 2005. Cosby did not testify.
Defense lawyers during the trial emphasized discrepancies in Constand's statements to police in 2005 in an effort to undermine her credibility.
Prosecutors, meanwhile, used her testimony as well as the words of a second accuser, Kelly Johnson, to portray Cosby as a serial predator. Johnson told jurors Cosby sexually assaulted her in strikingly similar fashion in 1996.
In his decade-old depositions, Cosby said he gave Constand Benadryl, a common allergy drug whose side effects can include drowsiness. He called the pills her "friends" without telling her what they were, and admitted to giving other young women Quaaludes, a sedative, in the 1970s.
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