On Friday, Gary Taylor, 26, appeared in the dock of court 11 at Belfast Crown Court, the same dock he stood in to be convicted of murdering 15-year-old Thomas Devlin.
Taylor confirmed his name and then pleaded guilty to trying to escape lawful custody and two counts of assaulting the two prison escort group officers on 3 January last year.
No facts were opened officially to the court and no reports were ordered given Taylor's most recent conviction. But it is understood the charge relates to the killer trying to escape after being taken to hospital, lashing out at the two officers in the process.
Taylor is originally from Mount Vernon in north Belfast, but his address on court papers was given as c/o Maghaberry Prison.
Jailing him on Friday, Belfast Recorder Judge David McFarland ordered that he serve the 12 month sentence consecutively to his life term.
Although defence lawyer Mark Farrell submitted that was an incorrect approach to the case, Judge McFarland told him bluntly: "You can appeal me if you want."
"He has to be punished for this so on the expiry of the term he is to serve another year," said the judge, adding that if Mr Farrell was correct, "that means he can try to escape everyday and he doesn't get punished for it."
The sentence is now set for review next week.
Fifteen-year-old Thomas was knifed to death near his north Belfast home while out buying sweets and drinks with friends on a warm summer's evening in August 2005.
Having stalked their victims, Taylor and 29-year-old Nigel Brown launched their attack on the Somerton Road, not far from Thomas' house.
The teenager suffered multiple stab wounds to the chest, abdomen, right upper arm, hip and face while his friend, Jonathan McKee, was also attacked and stabbed in the stomach.
On Thursday, at Belfast High Court, Brown's tariff of 22 years was reduced to 20 years.
However, the Lord Chief Justice Sir Declan Morgan upheld Taylor's sentence, one of the longest ever handed down by a Northern Irish court.
Lord Chief Justice Morgan pointed out that Taylor had gone out armed with a knife intent on carrying out a random and motiveless killing.
He said: "Murders on such a basis naturally strike fear in the minds of those within the local community because such conduct is the mark of the serial killer."