A self-confessed "monster" who strangled a teacher on a date before sexually assaulting her corpse has been convicted of choking a prison officer.
Carl Langdell, 27, was jailed for 26 years in June after admitting murdering Katie Locke, 23, at a hotel in Hertfordshire on Christmas Eve 2015.
In May, while on remand in HMP Bedford, he attacked Dean Adamson when the officer would not open a cell door.
A Luton Crown Court, Langdell was sentenced to a further three years.
In the witness box, Mr Adamson said he was working upstairs in the office on F-wing on 4 May when the attack happened.
The officer said: "He (Langdell) used to go to a cell with two other prisoners for a cigarette and tea break, but it was locked.
"He shouted up 'Get this door open downstairs', I said 'There are five other cells open. You can have a cigarette in one of them'."
Langdell then swore at the officer and another prison officer.
Mr Adamson said: "At the bottom of the stairs he walked aggressively to me and me punched me in the right eye.
"He got me in a headlock and tried to choke me. I was thinking he was going to kill me."
Other prison officers arrived and restrained Langdell.
The court heard that the prison officer spent four months off work with tendon and ligament damage.
Under cross-examination by David Smithet, Mr Adamson denied he had "over egged the pudding" in his account.
The jury was told that Langdell was a serving prisoner but not that he had committed murder.
Langdell, originally of Cheshunt, Hertfordshire, who did not give evidence, is serving his sentence at Frankland Prison, Durham.
He denied causing actual bodily harm but was found guilty by the jury.