Luca, aged 16, was last seen in the town on Monday 11 April.
Luca is described as 5ft 8ins tall with black collar length hair. He was last seen wearing a navy jacket and a Nike tracksuit, with a brown Montcler beanie hat and black Nike trainers.
Luca may be in the Ilford, Kent , Watford or Glasgow areas.
If you have seen Luca since he was reported missing or have information about where he has been, please call Hertfordshire Constabulary’s non-emergency number 101.
If you believe you are with Luca now or have seen him in the last few moments, please call 999 immediately.