The Los Angeles County district attorney has declined to bring criminal charges against comedian Bill Cosby stemming from sexual assault allegations by two women over separate incidents, one dating back to 1965 and the other to 2008, prosecutors said on Wednesday.

The district attorney, Jackie Lacey, determined prosecution was barred in the earlier case by the statute of limitations and in the latter case by insufficient evidence for a felony charge and the statute of limitations for misdemeanours, her office said in a statement.

The Los Angeles ruling, which does not name the two accusers, comes a week after Cosby was criminally charged in Pennsylvania with sexually assaulting a woman in his home near Philadelphia after plying her with drugs and alcohol in 2004.

The woman in the earlier Los Angeles case said she was 17 when raped by Cosby. The woman in the later case, who identified herself through an attorney as Chloe Goins, was 18 at the time she said she was sexually assaulted, prosecutors said. Both said Cosby plied them with alcohol.

The Pennsylvania case, filed just before the statute of limitations for criminal prosecution in that state was due to lapse, stems from allegations by a former Temple University employee, Andrea Constand — a Canadian — who settled a civil case against Cosby for an undisclosed sum in 2006.

The Pennsylvania case marked the first and only criminal charged brought against the once-beloved entertainer whose father-figure persona has been marred by dozens of similar accusations, some dating back decades. 

On Wednesday, a Pennsylvania state courts spokesman said Cosby's Jan. 14 preliminary hearing is being rescheduled, The Associated Press reported. Cosby's defence lawyers sought a postponement to give them more time to prepare.

L.A. accuser pursuing civil suit

Cosby, best known for playing Doctor Cliff Huxtable, the family patriarch in the long-running hit television sitcom The Cosby Show, has acknowledged marital infidelity but has denied any allegations of sexual misconduct.

"We are satisfied that the Los Angeles D.A.'s Office fully and fairly evaluated all the facts and evidence, and came to the right conclusion," Cosby's legal team said in a statement.

Los Angeles County prosecutors, citing the statute of limitations, previously declined to bring a criminal case in connection with a woman who reported she was molested at age 15 by Cosby at the Playboy Mansion in 1974.

Goins said she, too, was sexually assaulted during a party at the Playboy Mansion, in summer 2008, after Cosby served her an alcoholic beverage that made her dizzy and escorted her to a bedroom. Goins told investigators she awoke to find her clothes off and Cosby at the foot of the bed biting her toe as he appeared to be masturbating.

Prosecutors said they were unable to substantiate that Cosby or his accuser attended the party in question, nor could they corroborate her account with a friend identified as a potential witness.

In the 1965 case, the accuser reported she was raped by Cosby after he bought her drinks at a Hollywood jazz club, according to prosecutors.

Lawyers for both women issued statements expressing disappointment in the district attorney's decision while acknowledging the difficulties posed by the passage of time. Goins' attorney, Spencer Kuvin, said her civil suit against Cosby was proceeding.