Defence lawyers called to the stand a detective who led a 2005 investigation into claims that Mr Cosby drugged and molested a woman at his home in 2004.
The embattled star, 79, earlier told a judge he would not testify to defend himself against those allegations.
Mr Cosby denies the charge and his lawyer has said she agreed to sex.
Andrea Constand, the 44-year-old at the centre of the case, says the alleged incident happened during a visit to his home to seek career advice.
Dozens of women say he assaulted them, but statutes of limitation rules mean he is on trial for only one allegation.
Mr Cosby arrived at court on Monday with his wife, Camille, who made her first appearance at the high-profile trial in Norristown, a suburb of Philadelphia. She is the first family member to join him.
He told Judge Steven O'Neill that he had decided not to testify after speaking with his lawyers.
Detective Richard Schaffer appeared for just six minutes on the defence's behalf, in which he told a jury that Ms Constand had visited Mr Cosby at an out-of-state casino.
Defence lawyers have sought to discredit Ms Constand by suggesting the pair were in a romantic relationship and she had changed her story several times during a previous investigation.
In his closing argument, Mr Cosby's lawyer Brian McMonagle said while his client had been unfaithful to his wife, he did not commit a crime.
They pointed to dozens of phone calls she made after the alleged incident and the casino visit.
"This isn't talking to a trustee. This is talking to a lover," he said of one call that lasted 49 minutes.
In 2006, the comedian settled with Ms Constand after providing an undisclosed cash sum to her.
Mr Schaffer also said police knew Mr Cosby had vision problems more than a decade ago, supporting the actor's claim that he is blind.
Judge O'Neill rejected a request to call the defence's second witness, a woman who worked with Ms Constand at Philadelphia's Temple University, where Ms Cosby met the accuser.
The prosecution rested its case on Friday after five days of testimony from witnesses including Kelly Johnson, who claims Mr Cosby drugged and sexually abused her in 1996 under similar circumstances.
Prosecutors were expected to deliver their closing arguments and the jury could begin deliberating as early as Monday afternoon.
The case is seen as the biggest US celebrity court case since the murder trial of former American football player OJ Simpson in 1995.
If convicted, Mr Cosby faces up to a decade in prison.