Two men from Camden have been questioned over the death of a 15-year-old boy in Islington on Friday
Detectives said a 21-year-old man, from an address in Camden was arrested on suspicion of murder on Wednesday March 4.
He remains in custody at a central London police station.
In the early hours on the same day, a 17-year-old, also from an address in Camden, was arrested.
He has been released on bail pending further police enquiries until a date in mid-April, officers said.
Alan Cartwright, 15, was knifed while cycling along Caledonian Road, with friends at about 7pm on Friday.
He managed to continue cycling a short distance after the callous attack but soon collapsed and was pronounced dead at the scene later.
Detectives investigating the murder released CCTV footage of the moment he was attacked while cycling near the junction of Copenhagen Street.
A post-mortem examination on Monday March 2 gave the cause of his death as a single stab wound to the chest.
Police are asking anyone with information to call the incident room on 020 8345 3734 or contact Crimestoppers anonymously on 0800 555 111 or via crimestoppers-uk.org.
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