Philadelphia abortionist Kermit Gosnell on Monday was convicted on three of the four first degree murder charges for killing babies who had been born alive.

Gosnell, 72, could face the death penalty for the murder charges. The jury will hear arguments for and against a death sentence a week from Tuesday.

The unborn babies were known only by letters, and Gosnell was convicted of the murders of Baby Boy A, Baby C and Baby D at his Philadelphia clinic, the Women's Medical Society.

Baby Boy A was killed after Gosnell induced delivery on his mother, who was almost 30 weeks pregnant. Gosnell severed the baby's spine and put his body in a shoebox for disposal, joking that the baby was so big he could "walk me to the bus stop," the grand jury report said.

Baby C moved and breathed for 20 minutes after delivery before an assistant cut the baby's spinal cord.

Baby D was delivered into a toilet. A clinic staffer told the grand jury that the baby moved and looked like it was swimming when another staffer removed the baby from the toilet and cut its neck.

The abortionist was found not guilty in the death of Baby E, who a witness said cried before Gosnell killed it and put it in a waste bin.

Gosnell initially faced seven counts of first degree murder for the deaths of infants who were allegedly killed after being born alive.

Judge Jeffrey Minehart threw out three of the infant murder charges for unstated reasons. Gosnell's attorney had argued that there was no proof the babies had been born alive.

The abortion doctor was found guilty of involuntary manslaughter in the death of a patient who died of an overdose in 2009. Prosecutors had sought a third-degree murder charge in her case, saying Gosnell let his untrained and unlicensed staff give the 41-year-old Bhutanese immigrant woman a fatal combination of drugs.

The abortionist was also convicted of infanticide in the death of Baby A and conspiracy in the deaths of babies D and C.

Gosnell faced over 250 charges, including racketeering, conspiracy and violations of Pennsylvania's late-term abortion ban. He faced more than 200 counts of breaking a state law that requires a 24-hour waiting period on abortion.

The gruesome testimony at the trial included reports that Gosnell and his staff snipped the necks of over 100 babies who survived abortions. One doctor at the clinic testified that the procedure was "literally a beheading."

The grand jury report said that most of the acts could not be prosecuted because Gosnell destroyed the files.

Gosnell's name became a rallying cry for pro-life advocates who lamented a lack of major media coverage of his trial. Their efforts on social media helped draw attention to the case.

Lila Rose, president of the pro-life group Live Action, said Gosnell's "gruesome and inhuman crimes" had "cried out for justice."

"Even as we celebrate this verdict, we honor and mourn as well those innocents who did not receive 'their day in court' – and we must remember that Gosnell is not an outlier within the abortion industry," Rose said May 13.

Jack McMahon, Gosnell's attorney, said his client was "disappointed" and "upset" over the verdict. McMahon said the jury "obviously took their job seriously."

"The verdict should be respected based on their effort," he said, Fox News reports.

The jury had said it was deadlocked on two charges early on Monday. It was not reported which charges had caused the deadlock.

Gosnell's clinic had minimal state oversight through 1993 and no oversight since then. The practices at his clinic were not discovered until a Federal Bureau of Investigation and Drug Enforcement Agency raid was conducted in February 2010 to seek evidence of illegal distribution of prescription painkillers.

Investigators found blood-stained rooms and filthy equipment. The clinic stored aborted fetuses in a basement freezer in plastic food containers and bags next to staff lunches. Gosnell kept severed feet of unborn babies preserved in specimen jars, allegedly for future identification or DNA samples.

Staff allegedly sent women to give birth into toilets, a doctor allegedly spread sexually transmitted infections to women through poor sanitary standards, and a 15-year-old staffer administered anesthesia to patients. The clinic allegedly gave better treatment to white patients.

Several of Gosnell's former employees have pleaded guilty to murder and other charges.

The exposure of Gosnell's clinic resulted in the firing of two high-ranking Pennsylvania health department officials and tougher rules for Philadelphia abortion clinics, none of which had been inspected in 15 years.

Gosnell had also operated a clinic in Delaware.

He performed thousands of abortions over his 30-year career, making about $1.8 million per year. Authorities found $250,000 hidden in a bedroom when they searched his house. He still faces federal drug charges, Fox News reports.