Police in Durham Regional are warning the public about a high-risk offender who is set to be released on Sunday.In a community safety alert issued on Saturday, authorities said 48-year-old Keith Theodore Constantin has a long history of serious criminal convictions, including sexual assault with a weapon, robbery and posession of explosives.Detectives said he has repeatedly violated probation orders in the past and poses a significant risk to the community, especially children.Authorities said they will continue to monitor Constantin’s whereabouts and activities. He is required to wear a GPS monitoring device at all times and abide by a curfew from 7 p.m. to 7 a.m.Constantin is expected to report to the Durham Regional Police Service on a weekly basis and is not permitted to associate or communicate with anyone under the age of 16, or engage in any activities that involve contact with minors.Other conditions of his release include a prohibition on any weapons, drugs or alcohol.He is not permitted to use the internet or other digital networks, and cannot attend any public place like a mall where persons under the age of 16 are present or can be reasonably expected to be present unless accompanied by someone over the age of 21.Police advise the public to report any suspicious behaviour.