Stephen Alexander Marshall (August 9, 1985 – April 16, 2006) was a 20-year-old American-Canadian man who travelled from Nova Scotia to Maine with the intention of shooting and killing convicted sex offenders in an act of vigilantism.

[citation needed] On April 13, 2006, Marshall left his North Sydney (now part of Cape Breton Regional Municipality) home in Nova Scotia, driving to visit Houlton, Maine, where his father lived.

[11] He began by driving on Interstate 95 towards the houses of registered sex offenders in LaGrange, some of which he passed, though he continued towards Milo, where, according to police, he likely drove on State Route 16.

Throughout the multiple Milo residences of sex offenders that he drove by, Marshall chose the home of 57-year-old Joseph Gray, who, at around 3 a.m. on April 16, was shot and killed through his front window.

[citation needed] Later that morning, at 8:15 a.m.,[7] Marshall arrived at a mobile home in Corinth, resided by 24-year-old registered sex offender William Elliott, and knocked on his door.

[7] The Massachusetts Bay Transportation Authority (MBTA) were later notified about Marshall potentially being a passenger by Maine State Police,[13] who helped replace the bus after breaking down around Lewiston a few hours earlier.

[18] On August 27, 2005,[19] almost one year prior to Marshall's murders, 35-year-old Michael Anthony Mullen from Washington state used the Whatcom County's digital sex offender database to shoot and kill two convicted child rapists:[14] 49-year-old Hank Eisses and 68-year-old Victor Vasques.