Officer John Ferraro, 37, left behind a lengthy suicide note before barricading himself inside his home and fatally shooting himself.  Sheriff's deputies were moving in to arrest him on charges of having sex with a minor.  He admitted he had sex with another teen who was a member of the department-sponsored Police Explorer's unit.  In the note he also said other Largo officers were doing the same.  That was over a year ago.  This week the police chief opened an inquiry to find out if his officers engaged in inappropriate conduct with Explorers, said Largo police Lt. Michelle Smith, who is conducting the probe.  According to, the investigation began after a WFLA-TV reporter requested Explorer records dating back to 1992 to examine whether they included allegations of improper sexual relationships.  As the department gathered the records, police officials became aware of the implications and launched the investigation.  Police Explorers are a division of the Boy Scouts of America with male and female members between the ages of 14 and 22.