The McHenry County Sheriff's Office is investigating a "possible crime" in the 6000 block of Acorn Court in unincorporated Crystal Lake, but have not disclosed the nature of the incident. There is no known threat to the public, McHenry County Sheriff's Deputy Sandra Rogers said Thursday morning, but there will be a continued police presence in this area. When asked the nature of the "crime," Rogers said she couldn't comment. Crime scene tape was not spotted in that block Thursday morning.