A 17-year-old arrested in Liverpool on suspicion of firearms offences has previously been questioned as part of the Rhys Jones murder investigation.
The 11-year-old was shot as he walked home from football practice
The teenager was arrested during police raids in the Croxteth area of the city on Monday night.
Merseyside Police confirmed that the youth was previously arrested by detectives investigating the shooting of the 11-year-old.
Rhys was shot dead as he walked across a car park in Croxteth Park in August.
Eighteen people have been held on suspicion of murder or conspiracy to murder but no-one has been charged.
Detectives are investigating a theory that the bullet was fired by a teenage gang member aiming for a rival.
The teenager was arrested after raids by Merseyside's specialist Matrix unit, which is dedicated to fight gang, gun and drug crime.
He is being held as part of a separate investigation to the Rhys Jones inquiry.
Five other people were arrested during the operation on Monday, which is also linked to the theft of wild birds' eggs. A number of eggs were also seized.