The man is suspected of carrying out assaults on as many as 300 to 400 boys between the ages of six and 12 from the mid-1970s to 2007.
Jorid Kile Berg, a police lawyer from the Follo district, said: "We do not exclude that the charge can be extended."
The police were alerted to the suspect by a former policeman who linked details in the media to a case he had been working on in 1999, where the defendant was a suspect.
"The accused has been in the police spotlight since the end of November 2007," the police said.
The tip led to a secret search of the man's home in January, when police took DNA evidence that eventually led to his arrest.
The suspect's brother is also a former police officer, but the police said this had no significance to the case.
The first registered assault the man is suspected of took place in 1976 to 1977, and the last on July 14, 2007.
The assaults occurred in several different parts in Norway.