McDuffie is a black male who stands about 5 feet 4 inches tall and weigh about 160 pounds.
A reward is offered for information that leads to his arrest. Anyone with information about McDuffie's whereabouts is asked to call the Raleigh Police Department's Detective Division at (919) 890-3555 or CrimeStoppers at (919) 226 CRIME.
Meanwhile, police arrested another man, Murad Terrell Taylor, 21, and charged him with accessory after the fact of murder.
Gagnon was found dead around 10 a.m. Saturday on Bringle Court. Police have not released how the 28-year-old was killed.
Three others have also been charged with the murder --Marcus Johnson, 21, and Darrell Lavine, 19, and Bravette Devon Chrisp, 18.
Zachary Colmore, 17, Ebony Johnson, 17, Louis Johnson III, 21, and Joshua Locus, 20 are all charged with accessory after the murder.
Police continue to investigate.
The arrests follow what has been a deadly few weeks in Raleigh. At least three people have been killed in the past week.
Authorities say Raleigh has relatively low crime. Since January police have investigated 22 murders, which is the total number of cases in 2007 alone. The year before, there were 19.
Officials say the city is changing and that may be the case for crime, but what seems like a dangerous trend may be just a temporary spike.
"I think if it is an issue that continues over an extended period of time then it does become a part of your image, but individual spikes are frankly just that individual spikes," said Harvey Schmitt with the Raleigh Chamber of Commerce said.
Schmitt remains optimistic that deadly scenes will not detract from the reason many move to Raleigh.
"It's not going to change the way we live our lives and the way that we go about our day-to-day business," resident Leslie Canale said.
Police say experience has showed them that crime in the first half of the year and the latter part of the year can be quite different. So it's still too soon to say if it is a growing trend.