Omasese Lumumba
Omasese Lumumba was a 32-year-old Black man from Zaïre (now the Democratic Republic of Congo), the nephew of the country’s assassinated prime minister Patrice Lumumba.
Following his uncle’s assassination, Omasase and his family faced imprisonment and torture and so were forced to flee. He eventually came to Britain to seek asylum; however, in 1991 he was detained in Pentonville Prison under the Immigration Act. He was reportedly severely depressed, agitated and repeatedly said he did not understand why he was being locked in a cell.
Omasese died after at least six prison officers restrained him in a cell in the segregation block. The coroner initially instructed a jury to not return a verdict of 'unlawful killing' or 'lack of care', because he said the cause of death could not be determined. However, in 1993, following instruction from the High Court, the coroner redirected the jury and they returned a verdict of 'unlawful killing'.
No officers were prosecuted for their part in Omasese’s death. In 1994, 45 MPs signed an early day motion calling for a full inquiry into his death and the brutal treatment of asylum seekers. The inquiry never happened.

It may well be that there is some overlap between "unlawful killing" and "lack of care" but this is not a good reason only to leave one of them. A different standard of proof applies to them - the criminal standard in the case of unlawful killing.
Tim Owen - Report on the inquest