Police say 42-year-old Holly Ann Applegate was staying in the same apartment as the 82-year-old victim and several others.
The 2:30 a.m. blaze last Sunday also injured a firefighter.
Applegate is being held without bail in Lehigh County on homicide, arson and other charges after her arrest Friday. It was not immediately clear if she had a lawyer.
Applegate has prior convictions involving drug and prostitution charges.
Information from: The Morning Call, http://www.mcall.com
