A third man has been charged with murdering an inmate in Pentonville prison.
New father Jamal Mahmoud, 21, died after being stabbed at the north London jail during an attack which left two others injured on October 18.
On Thursday, police said Joshua Ratner, 26, had also been charged with the killing.
He will appear by video link before Highbury Corner Magistrates' Court on January 5.
Two other men, Basana Kimbembi, 34, and Robert Butler, 30, have previously appeared in court accused of the murder.
Mahmoud was killed by a single stab wound, a post-mortem into his death determined.
The young father's murder ignited calls for an inquiry into the state of jails in England and Wales, with his family accusing the prison of "neglecting him".
Cuts to staff and resources by the Government meant the "tragedy" at the north London site was "no massive surprise", the Prison Governors Association (PGA) said at the time.
It followed a slew of warnings about safety behind bars, while Pentonville was last year singled out by former justice secretary Michael Gove as "the most dramatic example of failure" within the estate.
