A pedophile will usually exhibit a series of personality characteristics that are common in this type of offender. It is important to understand that these characteristics alone do not conclusively determine that a person is a pedophile. But if these indicators, combined with a pattern of behavior that arouses suspicion, are present then there may be enough probable cause to believe that the person is a pedophile.
He carries on what can be termed "a special relationship" with a wife. Often pedophiles have failed marriages due to their sexual interests but remain in the marriage to mask their true intentions. Sadly, the wife sometimes knows about her husband's preference, but prefers to keep quiet to avoid social stigma and disgrace.
He displays a fascination or unusual interest in children. If an adult has an inordinate amount of interest in pre-pubescent children, it doesn't confirm he is a pedophile, but it should at least arouse suspicion.
He makes frequent references to children in exalted or exaggerated terms such as "pure," "innocent," "God sent," "blissful" and other descriptive labels that seem inappropriate and excessive. Remember that a pedophile cannot help the way he behaves and therefore will inadvertently reveal aspects about himself during speech.
He has hobbies or interests that commonly belong in the realm of a child's world such as toy collecting, building models of cars or planes. His home or room is decorated in a child's theme. And often, that theme will reflect the age bracket of his preferred victim.
He is over 30 years of age, single and has few or no friends his own age. He may also have frequent and unexplained changes of residence. He may be unable or unwilling to discuss why he lost his last job. He may have a military discharge that he cannot explain and a past that he can not easily talk about.
He has systematic and prolonged access to children. Pedophiles, because of the wide age disparity between themselves and their victims, cannot just hang around children. The pedophile has to find a way to legitimize his contact with kids. He usually accomplishes this by obtaining employment in a field where he is forced to deal with children on a daily basis. Jobs like schoolteachers, bus drivers, camp counselors, photographers and sports coaching(14) serve their needs perfectly. They will always volunteer for activities in which they are left alone with children with no parental supervision (Lanning, p. 19).
http://www.crimelibrary.com/criminal_mind/psychology/pedophiles/7.html?sect=2