A jury has found Sherry Fleming of Southport guilty on three counts of arson and one count of attempted arson.
She was found not guilty on two other counts of arson; the jury was undecided on a sixth arson charge.
Fleming, 53, had been accused of setting six fires and attempting to start another in her neighborhood between 2009 and 2010.
She had confessed to starting the fires but during her testimony said she confessed to protect her grandson from being arrested.
She claimed the lead investigator in the case forced her confession.
The judge has accepted the partial verdict and has discharged the jury.
