The Calgary Homeless Foundation voted Monday to remove one of its board members hours after it was revealed that the 62-year-old man is accused of using the date-rape drug GHB to sexually assault a teenage boy.

Robin Adair Wortman, 62, was arrested Sunday after allegedly chasing another victim with a knife as he fled the man's apartment.

The 19-year-old man, who had gone to the suspect's home in the 1000 block of 16 Avenue S.W., escaped unhurt, police say.

Police said they have been investigating Wortman since January, when a 17-year-old boy alleged that he was sexually assaulted by the older man.

'Given GHB to incapacitate him'

Investigators allege Wortman chose the youth as a victim because he was vulnerable.

"The teen accepted what he thought was crystal meth, but it is also believed he was given GHB to incapacitate him before he was sexually assaulted," said Staff Sgt. Melanie Oncescu of the Calgary police child abuse unit.

The teenage victim has been getting support through the Sheldon Kennedy Child Advocacy Centre.

Calgary police Sgt. Melanie Oncescu confirmed that Wortman was arrested Sunday. (CBC)

In the wake of the allegations, the Calgary Homeless Foundation (CHF) held an emergency meeting on Monday and voted to remove Wortman from the board pending the outcome of the charges against him, CHF president Diana Krecsy told CBC News.

"The Calgary Homeless Foundation is shocked upon learning these allegations, but we have a deep concern for the well-being of the youth, who we believe has demonstrated courage in coming forward," she said.

Wortman is charged with sexual assault in connection with the underage victim and assault with a weapon in connection with the 19-year-old man.

Wortman was also charged with two counts of communication to procure sexual services from victims under 18.

He was not previously known to police, Oncescu said.

He will be in court on March 15.