At the time of the fire, Mitchell had rented an apartment upstairs at 40 Randolph Ave.
Charges include four counts each of first- and second-degree arson, two counts of reckless endangerment and one count each of first-degree malicious burning and insurance fraud.
Mitchell was being held on $125,000 bond Thursday night at the Washington County Detention Center.
The cause of the blaze was determined to be suspicious almost immediately, said Hagerstown Fire Battalion Chief Randy Myers at the time. No one was hurt in the 12:23 a.m. fire that spread to 42 Randolph Ave.
Capt. Justin Mayhue of the Hagerstown Fire Department said firefighters quickly learned that two of the apartments in the building were vacant. Only one was believed to be occupied at the time of the fire and that resident was coming out of the building when firefighters pulled up, Mayhue said last May.
"That was a woman who was coming from the 38 Randolph Avenue side," Mayhue said Thursday night.
The fire was believed to have started in one of the vacant apartments on the second floor, Myers said last May.
"This is the culmination of a lot of hard work by our fire marshals, the Western Maryland Regional Crime Lab and the FBI Laboratory in Washington, D.C., and the Washington County State's Attorney's office," acting Hagerstown Fire Chief Rick Kipe said.
Mitchell's charges carry the following possible penalties on each count - 30 years in prison and/or $50,000 fines for first-degree arson charges; 20 years in prison and/or $30,000 fines for second-degree arson; and five years and/or $5,000 fines for insurance fraud, malicious burning and reckless endangerment.
Last May, fire officials said the apartment building at 38-40 Randolph Ave. was owned by Hagerstown Realtor Barbara Joy.