London, February 14 : Cops probing Chris Brown's alleged assault on his girlfriend Rihanna are also trying to find out whether an injury that latter covers by wearing an eye patch also resulted from a bust-up in the past.

Police sources in Los Angeles have revealed that Rihanna suffered a scratched cornea last year, following which she began wearing a patch to cover her red and sensitive eye.

The `Umbrella' star suffered a bloody nose, swollen lip and facial bruising in an alleged bust-up with 19-year-old R `n' B star Brown before last Sunday's Grammy awards.

Those investigating the case say that they are also trying to find out whether there exists any history of violent rows between the pair.

"We're investigating if her eye injury could have been caused by Brown," the Sun quoted an LAPD source as saying.

"There could be an innocent explanation - but police believe Rihanna has previously refused to make a complaint against Brown. She is now being asked about her past injuries and is beginning to open up about incidents in their relationship.

"We're talking to her friends and management, who say she's appeared with mysterious marks or injuries before, but always refused to explain what happened.

"There was one instance when she suddenly appeared with an eye patch, saying her cornea had been scratched," the source added.

Brown was charged with making threats following Sunday's alleged episode. (ANI)