Amy Winehouse's father "won't rest" until he finds out how she died.

Mitch Winehouse has vowed to leave no stone unturned as he tries to found out the truth behind his daughter's tragic passing at her home in Camden, north London, on Saturday afternoon (23.07.11) at the age of just 27.

He told a friend: "How did my little girl die? I won't rest until I find out."

The former taxi driver is said to be "in pieces" and is struggling to come to terms with the loss of Amy.

A source told the Daily Mirror newspaper: "Mitch is in pieces and is desperate to find out what happened in those last few hours. He just doesn't know what to believe. He went straight to his ex-wife Janis' home.

"He is acutely aware that it could be drugs that killed Amy, or that they may have triggered a pre-existing condition.

"At the moment, he is without a clue. It's all speculation. The lack of answers makes it even harder to come to terms with."

No drugs were found in her home by police.

Although an autopsy is expected to be carried out on the 'Rehab' singer's body today (25.07.11) to determine the cause of death, Mitch is said to be keen to adhere to Jewish traditions and bury Amy as soon as possible, with the family already having begun the first official phase of mourning - the 'sitting shiva' - for her.

Meanwhile, Amy's ex-husband Blake Fielder-Civil - who is currently serving a 32-month prison sentence for burglary and a firearm offence - is said to have "collapsed" in his cell when officers told him the devastating news.

According to The Sun newspaper, he said: "I'm beyond inconsolable ... my tears won't dry. I will never ever again feel the love I felt for her.

"Everybody who knew me and knew Amy knew the depth of our love. I can't believe she's dead."

Blake - whose turbulent relationship with the star came to an end in 2009 - was granted a visit from his current girlfriend Sarah Aspin, the mother of his newborn baby son Jack, yesterday (24.07.11), who described the former couple as "soulmates".

She added: "He is devastated and shattered. He just can't take it in that she's dead and he'll never see her again. Blake is the father of our son. But I saw him and Amy together and I know they were really in love and they were soulmates.

"She always loved him and he always loved her - but it was just never going to work. Basically they couldn't live with each other and they could not live without each other. It is hard for me knowing he still loved her, but I do understand his feelings."