Nicole Gross, 15, and Mary Gross, 12, were trapped in their second-floor bedroom when the fire ripped through the house at 220 Old Route 40 in Hancock on Monday about 10:45 p.m.
"This certainly stands as one of the more appalling, one of the more sickening cases I've had to deal with," Strong said during a news conference Friday afternoon at the Maryland State Police barracks in Hagerstown.
The girls' mother, Melissa Lindeman, escaped from the home by breaking a first-floor window and jumping out, fire officials have said. She was hospitalized with injuries she received when she jumped through the window, the fire marshal said.
Lindeman was listed as a patient at Winchester (Va.) Medical Center earlier in the week, but no longer was there Friday afternoon, a receptionist there said.
Meyers had been treated for smoke inhalation.
The four had been living in the home since August 2008.
Meyers on Thursday told Maryland State Police he set the fire, according to allegations in charging documents filed by a state police homicide investigator.
Meyers told investigators he went to the basement, sprayed lighter fluid on the electrical panel and bed near a furnace, and used a cigarette lighter to ignite a piece of paper, which fell on a sofa near the electrical panel, court documents allege.
Meyers said he tried to stamp out the fire, but the blaze spread quickly and he got out of the basement through an exterior door, investigators alleged in court documents.
Meyers, who was unemployed, told state police he set the fire in hopes of receiving donations from the community, according to court documents.
A medical examiner has determined the sisters who perished in the fire died of smoke inhalation, the Maryland State Fire Marshal said Thursday.
The medical examiner determined there were high levels of carbon monoxide in the girls' blood, State Fire Marshal William E. Barnard said during Friday's press conference. He said the girls were found in their bedroom.
Investigators found a smoke alarm in the debris, but were unable to determine whether it was in working condition, Barnard said. One alarm outside the sleeping area would have been compliant with the codes for older homes, he said.
Property records show the home was built in 1918.
Federal Bureau of Alcohol, Tobacco, Firearms and Explosives experts assisted with the investigation, and determined late Thursday that arson caused the fire, Barnard said.
Meyers was interviewed by Maryland State Police homicide investigators Thursday night, and charges were filed early Friday.
He is scheduled to be in Washington County District Court March 19 for a preliminary hearing.
Meyers has lived in Washington County for about 25 years, Assistant Public Defender Brian Hutchison said Friday in court. His client appeared in district court for the bond review from the Washington County Detention Center via closed-circuit television.
Meyers has two children -- a 13-year-old daughter and a 19-year-old son in the Navy, Hutchison said.
During the bond review hearing, Strong called Meyers a "danger to society" who has no real ties to the community.
Meyers had a previous reckless endangerment conviction, Strong said.
Meyers is charged with two counts of first-degree murder, one count of first-degree arson, one count of first-degree malicious burning, one count of second-degree malicious burning and two counts of first-degree child abuse resulting in death, records show.