Ontario Ombudsman Andre Marin received the Twitter messages shortly before he was scheduled to open a new investigation Thursday of the fatal shooting by police of Toronto teenager Sammy Yatim last month, the Toronto Sun reported Monday.
The messages, from "Joe Mayo," insulted Marin and claimed he is an al-Qaida member.
Marin identified the message-sender as Durham, Ontario, Regional Police Detective Constable Scott Dennis, whose Twitter account biography, Marin said, indicates his only goal in life is to "expose Andre Marin for the [leech] on society he is."
Marin did not explain how he learned Dennis was the sender, the newspaper said.
Durham Regional Police Chief Paul Martin said, on Twitter, Marin's "disturbing allegations" are being investigated.
"Emotions run high when you talk about police oversight. Now, in this case [referring to the Yatim case], a little higher than the normal temperature," Marin said.