State and federal officials released this sketch of the suspected NAACP office bomber in Colorado earlier this year. They arrested Thaddeus Murphy, a 44-year-old man from Colorado Springs, on Thursday. Reuters

Federal law enforcement officials have arrested a man in connection with a January explosion outside the building housing the NAACP's Colorado Springs headquarters. Thaddeus Cheyenne Murphy, 44, was taken into custody Thursday for the incident, the Denver Post reported. He told police he was not targeting the NAACP. Authorities are continuing to investigate his motive.

Unnamed sources told CBS News that Murphy's target actually was a tax preparation company that used to occupy offices in the NAACP building. The business reportedly mishandled Murphy's taxes and left him owing money to the IRS. Murphy was frustrated because the accountant in question, Steve Dehaven, wouldn't answer his phone calls, according to 9 News.

Officials allege that Murphy lit a road flare and pipe bomb near gasoline on Jan. 6 near 603 South El Paso St. It exploded, charring the building and sidewalk, but the gasoline didn't ignite. Nobody was injured, but police surmised the NAACP was targeted.

Witnesses saw a man matching Murphy's description leave the scene in a truck. When federal agents later searched his home, they found seven firearms and other explosive devices -- all illegal because Murphy has prior felony convictions for thefts and failure to appear in court. He was arrested on Thursday.

"The residents of Colorado Springs, and the occupants of the building in question, can rest assured that the person who allegedly placed the device is now in custody," according to a Department of Justice news release. The FBI; the Bureau of Alcohol, Tobacco, Firearms and Explosives; the Colorado Springs Police Department; and the El Paso County Sheriff's Office are all involved in the case.

Murphy has been charged with arson of a building and being a felon in possession of firearms. He could face $500,000 in fines and about 15 years in prison. Read the 17-page criminal complaint here.