A former Vancouver lifeguard has been charged after police received a tip on historic sexual assaults on young boys dating back four decades.

Abraham Kiewiet, facing five counts each of "indecent assault on a male" and "gross indecency," is now 70-years-old. Police said he was at the Vancouver parks department as a lifeguard, was a swim coach for the YMCA, and an instructor at the Vancouver Lifeguard School, during the time of the assaults.

So far, four victims have come forward since police launched the investigation in June and subsequently arrested the senior at his Vancouver home.

Online court records show charges stemmed from allegations on four different dates, three of them New Year's Days, between 1971 and 1979.

The victims who've come forward to police were between 11 to 17-years-old at the time.

"We believe there are other victims out there," said Sgt. Randy Fincham, Vancouver Police Department.

"For a case like this, as it's being 30-years-old, the investigation is challenging and there are obstacles."

Kiewiet was sworn in Vancouver Provincial Court Thursday. He has been released from custody with conditions. These include not seeking any employment where he's in a position of trust over a minor, not to be in any public place with minors, and not to possess weapons.

Police added they don't believe he's a flight risk because the allegations were from so long ago.

No pictures have been released of the accused, but police ask those with information to the case to call 604 717 0618.