- Madeleine disappeared in 2007 while on holiday with her parents in Portugal
- Police will make a new appeal for leads in her case Monday on the BBC
- Two sketches of a man spotted around the resort the night Madeleine disappeared are released
(CNN) -- It's been more than six years since Madeleine McCann vanished while on holiday with her parents in Portugal.
But neither her parents nor the detectives investigating her case are giving up on one day finding the little girl from Leicestershire, England.
Her disappearance is set to get renewed attention Monday when investigators make another appeal to the public on BBC's "Crimewatch," releasing two computer-generated sketches of a man spotted around the resort town of Praia da Luz on the day then-3-year-old Madeleine went missing. The sketches are based on descriptions from two separate witnesses.
"Today I am asking the public for their help. Whilst this man may or may not be the key to unlocking this investigation, tracing and speaking to him is of vital importance to us," Detective Chief Inspector Andy Redwood said in a statement Monday before the program, which will air in the United Kingdom, the Netherlands and Germany. "We have witnesses placing him in the resort area around the time of Madeleine's disappearance."
The man is described as white, between 20 and 40 years old, with short brown hair and a medium build.