Gosnell, 72, was accused of snipping the spines of babies born alive during illegal late-term abortions. Pennsylvania law prohibits abortions after 24 weeks of gestation.

Three other murder charges were dismissed earlier in the trial for lack of evidence.

The same jury was to convene May 21 to consider Gosnell’s sentence. Prosecutors were seeking the death penalty.

Gosnell was arrested in 2011 and charged with seven counts of infanticide and one count of murder in the case of a woman who died during an abortion.

Several patients and former employees testified about squalid conditions at the clinic, described by some as “a house of horrors.” Several former workers in the clinic, including Gosnell’s wife, Pearl, earlier pleaded guilty to charges including third-degree murder, racketeering and performing illegal, late-term abortions.

The involuntary manslaughter charge came in the death of Karnamaya Mongar, 41, of Woodbridge, Va., who was given repeated doses of powerful drugs to induce labour and sedate her.

The jury also found Gosnell guilty of infanticide, racketeering and more than 200 violations of Pennsylvania laws, for performing abortions past 24 weeks or failing to counsel women seeking abortions 24 hours before providing the procedure.

The case against Gosnell took shape after a team of health inspectors and investigators looking into the drug trade raided Gosnell’s clinic in February 2010.