The relatives of a pregnant woman brutally stabbed to death by a man who spent just five years in a secure mental hospital before being let out are claiming victory after a government minister promised to review sentencing guidelines.

Abiodun Ilumoka was beaten and fatally knifed by her illegal immigrant boyfriend at their home in Essex Road, Islington, in 2008. Her killer, Ben Anabah, was detained indefinitely and sentenced to deportation after pleading guilty to manslaughter.

But her family were horrified when they found out he had been on escorted leave from the institution, possibly in Islington, a number of times this year without them even being told, which led them to launch a campaign for a change in the law in such cases.

With the help of the Gazette and Islington South and Finsbury MP Emily Thornberry, the matter was debated in the House of Commons last Thursday with justice minister Jeremy Wright pledging to look at guidance given to judges as well as deporting Anabah when he is released from hospital.

Yemi Ilumoka, Abi’s sister, said: “It’s a great result and we are really pleased. He knows he has met his match and this family will not go away.

“He met us after the debate to express his condolences in person and confirm he will take action to redress what’s gone on.

“Sometimes politicians say one thing and don’t follow it through but the beauty of this is he has made these promise and it’s on official record, so he can’t back out. And if he does, he will have nowhere to hide.

“It’s more or less everything we have campaigned for.”

Ms Thornberry began the debate by describing how Anabah was charged with murder and child destruction before pleading guilty to manslaughter by way of diminished responsibility, and would otherwise have received a life sentence.

She said: “The victim’s family therefore expected that he would be confined indefinitely to a psychiatric hospital and eventually removed from the United Kingdom – and, frankly, that is what the public would have expected as well.

She added: “Why would a patient who has killed someone less than five years before be eligible for release, and how could a restricted foreign national patient with a recommendation for deportation also be eligible for release, or even be considered for release?

“That is simply unacceptable and puts this issue into context.”

Mr Wright said “there should not be a gap or hiatus between Mr Anabah’s release from hospital and his removal from this country” and he had spoken to immigration authorities who would “make every effort to ensure that that is the case”.

He added: “We will look again at the point about [judges’] guidance, as I said, and I hope that she understands the seriousness with which we take this case and recognises the changes I have outlined to the notification for victims, which I hope will prevent some of the distress that her constituents have had to endure in relation to this case.”

Former Highbury Fields School pupil Abi was just a few months away from becoming a mother when she was killed by her partner in June 2008.

Police rushed to her house and discovered Anabah with blood on his hands and mother-to-be Abi in the kitchen.

She was rushed to hospital but died. Attempts to save her baby, including an emergency caesarean, were also unsuccessful.