Deadlocked after 12 days of deliberations, the jury told Superior Court Judge Larry Paul Fidler it could not reach a verdict and was split 10-to-2 after six ballots, The Los Angeles Times reported. It was not immediately known which way the panel majority was leaning.
Fidler asked jurors if there was a possibility of reaching a verdict; each said no.
The 76-year-old music icon has been on trial since April for the 2003 shooting death of Clarkson, who was found shot in the face in the foyer of Spector's home.
The jury received the case Sept. 10 after listening to testimony of more than 70 witnesses. The panel said on Sept. 18 it was deadlocked, 7-to-5 -- prompting Fidler to withdraw jury instructions and give the jury new directions that court observers considered to be broader.
Prosecutors contended that Spector shot Clarkson. The defense countered Clarkson accidentally killed herself.