A woman wept as she told how her life has become "empty" after her husband died in custody in September, while he was visiting London.
Mrs Ogboru says she is "devastated" by her husband's death
Frank Ogboru, 43, a Nigerian national, died after police restrained him outside a block of flats in Woolwich, in south-east London.
Mr Ogboru's death is currently being investigated by the Independent Police Complaints Commission (IPCC).
His wife and the family lawyer met officials at the IPCC on Thursday.
Speaking to BBC London, Christine Ogboru said: "I feel so devastated, so empty because Frank was my best friend, we are inseparable, but now the best thing of my life has been taken away from me... I'm alone in this wide world."
On 26 September, Mr Ogboru, a businessman, had an argument with a woman in the flat in which he was staying.
Mr Ogboru died in custody on 26 September
Police said force had to be used to restrain him. Paramedics were called to treat him after he fell ill but he died before reaching the hospital.
A post-mortem examination proved to be inconclusive.
Allens Agbaka, the family lawyer, said he was concerned about what he called the slow pace of investigation of the case.
"The defence which the Met have proffered is 'we were trying to restrain him, in the course of which he died'.
"The question we asked was what was the force used? Was it a reasonable force in the circumstances... my opinion is it was excessive," he said.
Mrs Ogboru, who came to London last week, said she wanted justice.