Richardson was last seen in the Denver area in 1992. He lived in the area of Lowell Boulevard and West 29th Avenue in north Denver.
He also frequented the Idaho Springs area, according to Denver Police detectives.
Both locations are among three that Denver Police have recently explored in connection with a suspect accused of sexually assaulting another boy, a 9-year-old, from 1999 to 2001.
The Denver District Attorney's office charged 62-year-old John Taylor on Monday, alleging he assaulted the 9-year-old between 1999 and 2001.
The charges allege that Taylor was a neighbor of the victim's mother and assaulted the victim while the boy was in his care.
Taylor faces three counts of sexual assault on a child, four counts of sexual assault on a child by a person in a position of trust and one count of sexual assault with a pattern of abuse. Taylor is in jail on $250,000 bond after police arrested him Feb. 21.
9Wants to Know has confirmed Denver Police believe Taylor may have assaulted other victims who have not come forward. On Feb. 24, police asked the public to call with any information.
Officers identified three areas where Taylor lived or may have frequently visited: the 4800 block of West 14th Avenue, Lowell Boulevard at West 29th Avenue and the Idaho Springs area.
Two of those addresses are locations where Richardson spent time.
Denver Police will not officially say if child sex assault charges against Taylor and Richardson's disappearance are connected.
Monday, police released a picture of Richardson from 1992 and an artist's rendering of what he might look like now.
Taylor has been arrested on sex assault allegations before.
Denver Police arrested Taylor in 1991 on allegations of sexual assault on a child and a sex offense of exploitation of a child. Though he was formally charged, the case against him was dropped, according to Denver District Attorney spokeswoman Lynn Kimbrough.
In 2002, he pleaded guilty to possessing a schedule 4 controlled substance. A judge sentenced him to one year of unsupervised probation.
Taylor's next court appearance will be Wednesday for his formal advisement of the charges.
If you have information on Taylor or the disappearance of Ian Richardson call Crime Stoppers at 720-913-STOP (7867.) You can remain anonymous.
If you have a tip for investigative reporter Jace Larson, e-mail him at firstname.lastname@example.org.
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