A killer nicknamed the Black Widow for murdering her husband with a drugs overdose may only serve 16 years behind bars for her "cold and calculated" crime.

Dena Thompson, a bigamist described by a judge today as "scheming, lying and highly manipulative", was convicted of murdering Julian Webb at the Old Bailey, in December 2003.

She had used the hot spice of his favourite curry dish to cover up the bitter taste of the the painkillers and aspirin she used to kill him on his 31st birthday in June 1994.

Aged 34 at the time of the killing, she was only caught after Mr Webb's body was exhumed in the wake of her acquittal in 2000 on a charge of attempting to murder her third husband, Richard Thompson, from Littlehamtpon.

Reviewing the case today at London's High Court, Mr Justice Ouseley said Thompson, formerly of Yapton, was "a scheming, lying, highly manipulative woman who could easily dupe men into doing her bidding.

"This was a cold and calculated murder, achieved through trickery and without remorse".

The judge said he had considered carefully whether Thompson's crime was so horrific that her minimum jail term - or "tariff" - should be set at 30 years or more.

However, after looking again at the evidence and observing that a financial motive for the murder had not been proved beyond doubt, the judge fixed her tariff at 16 years.

That means that Thompson can apply for parole in December 2019.

The judge said he had taken into account a moving statement from Mr Webb's mother, Rosemary, who spoke of her grief at losing her only child, a man who "had enjoyed life enormously".

Today's ruling does not change the fact that Thompson is serving a life sentence. Even when her tariff expires, she will only be freed if she can persuade the Parole Board she poses no serious danger to the public.

When released, she will remain on perpetual "life licence", subject to prison recall if she ever again puts a foot wrong.

Mr Justice Ouseley said Dena Thompson's 1991 marriage to Julian Webb was bigamous, although he had no inkling she was already married and his horrified mother only discovered the truth after his death.

Thompson murdered him by "tricking him somehow" into taking massive overdoses of aspirin and a pain killer on June 30 1994. It was the prosecution case that she used the hot curries he loved to disguise the bitter taste of the lethal overdoses.

Mr Webb's death was reinvestigated after Thompson's acquittal in 2000 on a charge of trying to murder her third husband, Littlehampton man, Richard Thompson. Mr Webb's body had to be exhumed as part of the inquiry.

At her trial, Thompson insisted Mr Webb had killed himself, but the jury disbelieved her.

Describing Thompson as "a scheming, lying, highly manipulative woman who could easily dupe men into doing her bidding", Mr Justice Ouseley said Mr Webb would have been extremely ill and suffered appallingly in the few hours before he died.

He added: "This was a cold and calculated murder, achieved through trickery and without remorse. There was neither mitigation, nor excuse".

Setting Thompson's minimum jail tariff at 16 years - three years longer than the 13-year tariff recommended by the judge at her trial - Mr Justice Ouseley concluded: "There are no mitigating factors. In particular there was clearly an intent to kill".