A young policeman. He was eager to be partnered with detective Luther but lacks experience. He proved to be loyal to Luther and a good friend.
DS Justin was a young policeman who was ambitious and eager. He was eager to be partnered with detective Luther because he considers him the best dectective in the field. He studied forensic psychology and criminology to post-graduate level and has a textbook knowledge of the last fifty years of crime-solving. Ripley is unwaveringly loyal - but he has his own ideas about what's right and what's not. He quickly discovers that while Luther burns brightly, those who stand too close are liable to get burned. In Episode 6, despite being the newest on the team, Justin is the only one who believes and can understand that Luther is innocent as where he holds down the rifle of a police marksman and yells to John, "Run!!". In this way he saves Luther's life, preventing him from being shot by a sniper, but he also helps in other ways too. DS Justin is initially penalised for his loyalty and is told that he will not be working in the team for at least a few years.
Luther invited Ripley to work with him again, and Ripley accepted his invitation. DS Erin Gray begins to work in a unit that investigate police officers, and targets Luther. Justin becomes involved in this investigation, much to Luthers disgust when he finds out. However, he steals the taped interview Justin gave in which he champions Luther as not having done any wrong to his knowledge. This leads Luther to introduce him to his new girlfriend, describing Justin as his mate and admitting that he loves him as such. A vigilante killer targeting men on bail shoots Justin in the chest and he dies from his injuries in the penultimate episode of the series.