Police raided Amy Winehouse's London home and later arrested four men - including her husband - in the operation, according to news sources.
The troubled singer was not arrested, and police did not reveal why her house was targeted but noted, "Investigations are ongoing."
Officers from the Metropolitan Police Service were seen entering the back of Amy Winehouse's residence in northwest London.
Amy Winehouse and her husband, Blake Fielder-Civil, were not believed to be in the home at the time the raid went down. However, Fielder-Civil was arrested and led off in handcuffs by plainclothes police later that day.
The four unidentified men ages 19-25 were arrested at addresses in East London on allegations of perverting the course of justice, police said.
A police spokesman would not mention Blake Fielder-Civil by name, and said only: "We arrested four men, two of them 25 years old, one 22 and one 19, in connection with an allegation of perverting the course of justice."
Blake Fielder-Civil goes on trial Monday on charges of inflicting grievous bodily harm with intent, over allegations he and another man beat up James King, a bartender. Police did not say why the alleged assault took place.
The Mirror said it had tipped off police after it received evidence there may have been an attempt to pay witnesses to change their stories.
Officials say an accusation of perverting the course of justice, like the grievous bodily harm charge itself, could carry a potential life sentence for Blake Fielder-Civil.
Amy Winehouse, who achieved fame last year with the hit single "Rehab" about her own refusing drug and alcohol treatment, has been dogged by allegations of substance abuse, no-shows at concerts and (to say the least) erratic behavior.
She, Blake Fielder-Civil and a mutual friend were arrested just last month in Norway for possessing cannabis and paid a fine.