A suspect was pictured walking away from the shooting
Police have arrested a suspected Camorra hitman caught on camera as he shot a man dead outside a bar in central Naples in May.
Images of the killing caused shock because they showed bystanders at the murder scene appearing largely unfazed.
Authorities said they had reluctantly released the images after months of investigations came to nothing.
Police did not immediately give details about how the suspect, identified as Costanzo Apice, was detained.
It was not immediately clear whether releasing the video footage had helped them find the suspect.
The killing occurred in daylight on 11 May. The victim was Mario Bacioterracino, described in media reports as a boss in the Camorra, the mafia-style organised crime group that is powerful in Naples.
The closed-circuit TV (CCTV) images that were eventually released at the end of October showed bystanders seemingly indifferent as the victim was shot at close range in the back and the head.
One woman is seen with a scratch card as the shooting takes place, then a man carrying a child walks calmly past the victim's body.
Interior Minister Roberto Maroni criticised the decision to release the video images, saying they "gave the impression of a Naples that is very different from the reality".