This is the Traces series by Malcolm Rose.
According to the TV Tropes page, the protagonist is Luke Harding, a sixteen-year-old forensic investigator whose partner is the Mobile Aid to Law and Crime ('Malc' for short).
Traces is a series of seven Science Fiction crime novels by Malcolm Rose. They center around sixteen-year-old Forensic Investigator Luke Harding and his partner in law, the Mobile Aid to Law and Crime (or Malc for short), as they solve crimes in an alternate England where blacks are the majority race and the southern parts of the country are derelict slums.
According to this excerpt from the Google Books preview of the first book, Framed!, Malc is an airborne robot.
The bunker had a high-security door and access was restricted. Now that Luke had graduated in criminology, though, he had a right of entry but his updated identity card had not yet been delivered. He pointed to the combination lock and said, "Open it, Malc."
The airborne robot beamed the correct code into the mechanism and the door clicked open.
The plot summary on the Wikipedia page for the series notes that the setting is a future version of England in which children are taken from their parents at the age of five in order to be trained for specific jobs. The authorities also select life partners for people based on age and aptitudes, but Luke wishes to be with his musician friend, Jade Vernon, rather than his selected partner, a biologist.
The Traces universe is explicitly located in a future England, where the decayed and semi-abandoned South is supported and feared by the vibrant, successful North.
England is somewhat a benevolent dictatorship, but the dictator is a computer system. The country is run by the unnamed and generally benign Authorities, who remove children permanently from their parents at the age of five, to be raised in residential schools until they graduate. At this time they will take up the employment they have been training for. Adults are paired for life at the direction of the Authorities: partners are selected by local Pairing Committees based on age and aptitudes. The pairing is generally announced in mid-teens and Pairing takes place at the age of twenty. Most people are content to accept the direction given, but a recurring theme in the books is Luke Harding's dissatisfaction with the Pairing Committee system. As a scientist, when he reaches twenty he is to be paired with biologist Georgia Bowie despite his wish to be with musician and close friend Jade Vernon. Their struggle to be together is a central part of several of the storylines. Whether they will be paired is uncertain, but seemingly unlikely. Jade has played a significant part in multiple stories, but as a Forensic Investigator, most of Luke's work is in the Southern slums, while Jade's work is in the cultural centres of the North.
The Amazon UK plot summary for the first book, Framed!, covers most of the remaining plot points:
- Jade is Luke's secret girlfriend and an expert musician.
- Luke's nickname at school is 'Diamond.'
- A series of diamond-themed murders is committed and Luke becomes the prime suspect.
Luke Harding has barely had time to celebrate becoming the youngest ever person to qualify as a forensic investigator when Malc, his Mobile Aid to Law and Crime, calls him to their first case. A student has been mysteriously shot dead with an arrow. An elusive killer is at large and all the evidence points to Luke being the murderer himself...Imagine a place where technology rules...where London is a slum and the North is a cultural capital...where from the age of five, The Authorities decide your future. In this fascinating parallel world, quick-thinking Luke Harding is the youngest Forensic Investigator ever, aged just 16. Luke and his right-hand robot, Malc, make a top team. Together, they have the talent to crack any crime - and a good joke, too. Luke Harding has just qualified as an FI when fellow pupil Crispin Addley is shot dead by an arrow. Addley was on his way to beating Luke's record grades in Forensics. Then sports teacher and pairing committee chair Ms Kee killed. Kee had been irked that she had 'lost' sporty Luke to Science. Malc states Luke had motive to kill both people and Luke, ridiculous though it seems, has to accept this. Then Vince Wainright is murdered with a diamond cutter. Vince was to be paired with Jade, Luke's secret girlfriend. Luke must race to clear his name. He interviews colleagues, friends and enemies of the victims but there is no clear lead. The Authorities are threatening to take Luke off the case as he is the prime suspect. Luke then realises a connection between the murder weapons - a diamond cutter, a diamond-shaped arrow and a poisoning with the venom of a diamondbacked snake...Luke's nickname at school is Diamond. At the memorial service of Ms Kee, Luke hatches a plan to use special technology to try and expose the killer. Jade is an expert musician and has a new machine that can direct sound at a person like a laserbeam without people nearby hearing anything.
This last part of the Amazon UK plot summary for the first book notes that Malc saves Luke's life by taking a knife thrust meant for him. I've hidden it as a spoiler because it also reveals the name of the killer.
At the after-service gathering Jade directs whispers of guilt at some of the suspects. All act confused except for school nasty Ed Hoffman who, thinking the whole room has heard and he's been exposed, grabs a knife and lunges to stab Luke. Malc takes the blow, saving Luke's life. Hoffman is taken away.
