Police have described Mr Derdour as 5ft 8in (172cm), of mixed heritage, with a slim build. He is in 20s and was most recently seen with a moustache and facial hair.
He goes by many aliases, police say.
Police believe that there are people who may likely will have seen or spoken to the suspect and urge them to come forward.
Ch Supt Jason Stewart, who leads policing in Islington, said: “Adam’s family have suffered an unthinkable loss, and we believe someone out there knows something that could help us bring those responsible to justice.
“If you have seen this man in the days following Adam’s murder, please come forward. Even the smallest detail could be the breakthrough our detectives urgently need.
“Our intelligence suggests he frequents Holborn and the surrounding areas.”
He added that if anyone wanted to give information anonymously, they can call Crimestoppers.