The coroner who oversaw the inquest into the death of Amy Winehouse has resigned after her qualifications were questioned, her boss said Wednesday -- raising the possibility the investigation may have to be held again.

Winehouse's relatives said they were still absorbing the implications of the news and were seeking legal advice.

In October, Suzanne Greenaway ruled that the soul singer, who was found dead at her London home in July, had died from accidental alcohol poisoning.

Greenaway had been appointed an assistant deputy coroner in London in 2009 by her husband, Andrew Reid, the coroner for inner north London. But she resigned in November after authorities learned she had not been a registered U.K. lawyer for five years as required by the rules. She had practiced law for a decade in her native Australia.

Her resignation was not made public until Wednesday.

"I believed at the time that her experience as a solicitor and barrister in Australia satisfied the requirements of the post," Reid said in a statement Wednesday. "In November of last year it became apparent that I had made an error in the appointment process and I accepted her resignation."

Reid apparently broke no laws in appointing his wife but could have breached professional guidelines. She was one of several deputy assistant coroners.

The local authority, Camden Council, said it was confident Reid "had made an error in good faith" when he appointed his wife, but said the matter was being investigated by Britain's Office for Judicial Complaints.

Greenaway oversaw 12 inquests in Camden, the north London borough where Winehouse lived, and others in east London. Reid said he was "confident that all of the inquests handled were done so correctly" - but offered to hold those inquests over again if the families of the deceased wanted it.

Winehouse's family said it had not yet decided what to do. In a statement, the family said it was "taking advice on the implications of this and will decide if any further discussion with the authorities is needed."

A security guard found Winehouse dead in bed on July 23 at her home in Camden. The 27-year-old singer, known for her distinctive beehive hairdos and multiple Grammy-winning album "Back to Black," had battled drug and alcohol addiction for years.

At the October inquest, Greenaway delivered a verdict of "death by misadventure," saying the singer suffered accidental alcohol poisoning when she resumed drinking after weeks of abstinence.

The inquest heard evidence from a pathologist, Winehouse's doctor, the security guard who found her and a detective who described seeing three empty vodka bottles in her bedroom. It appears unlikely that a second inquest would produce a different conclusion about how she died.

"Back to Black" brought Winehouse global fame, and its updated take on old-time soul, jazz, rock and doo-wop earned five Grammy Awards. Although the singer was adored by fans worldwide for her unique voice and style, praise for her singing was often eclipsed by lurid headlines about her destructive relationships and erratic behavior. Winehouse herself turned to her tumultuous life and personal demons for material, resulting in hit songs such as "Rehab" and "Love Is a Losing Game."

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