A judge tossed three of eight murder charges Tuesday in the high-profile trial of an abortion doctor accused of killing babies prosecutors say were born alive at a clinic they dubbed "a house of horrors."

Dr. Kermit Gosnell, 72, still faces the death penalty if convicted on four remaining counts of first-degree murder involving babies he's accused of killing with scissors after they were born alive.

Judge Jeffrey Minehart did not explain why he dismissed the three murder counts but apparently felt he had not heard sufficient evidence from prosecutors that those three babies were viable, born alive and then killed. Much of the evidence during the five-week prosecution case has come from the recollections of former staff members, though their testimony was bolstered by graphic photographs of some of the aborted babies.

Prosecutors argued that the babies were viable and that Gosnell and his staff cut the backs of their necks to kill them.

"Why would you cut a baby in the back of the neck unless you were killing it?" Assistant District Attorney Ed Cameron asked.

The defense questioned testimony from staffers who said they had seen babies move, cry or breathe. Defense lawyer Jack McMahon argued that each testified to seeing only one movement or breath.

"These are not the movements of a live child," McMahon said. "There is not one piece _ not one _ of objective, scientific evidence that anyone was born alive."

The judge also upheld murder charges in a patient's overdose death. Gosnell is charged with third-degree murder in the 2009 death of 41-year-old Karnamaya Mongar, a recent refugee to the U.S. who died after an abortion at hiss Women's Medical Society.

McMahon argued that third-degree requires malice, or "conscious disregard" for her life.

"She wasn't treated any differently than any of the other thousands of other people who went through there," McMahon argued Tuesday, in a preview of his likely closing arguments.

Prosecutors might concede that point themselves at closings, and argue that patients were routinely exposed to unsanitary, intentionally reckless conditions at the clinic. Former staffers have testified that patients received heavy sedatives and painkillers from untrained workers while Gosnell was offsite, and were then left in waiting rooms for hours, often unattended, before Gosnell arrived for the late-night surgeries.

Despite that, the workers testified that they had never seen a woman go into distress before Mongar. Yet a 2011 grand jury report alleges that dozens of women were injured at Gosnell's clinic over the past 30 years. Some left with torn wombs or bowels, some with venereal disease contracted through the reuse of non-sterilized equipment, and some left with fetal remains still inside them, the report alleged. And the report blamed Gosnell for an earlier maternal death that was not charged.

Cameron, in defending the Mongar charge, said it stemmed from the circumstances at Gosnell's clinic. They included the repeated medication dosages given by medical assistants; the doctor's absence during most of her two-day visit; and the hour it took to open a locked side door and take her by stretcher to an ambulance.

The defense motions to dismiss the various counts Tuesday offered a preview of closing arguments, which could come within the next week, especially if Gosnell chooses not to testify. A gag order prevents lawyers from disclosing their strategy.

A string of character witnesses testified Tuesday afternoon for Gosnell's co-defendant, Eileen O'Neill. She is charged with three counts of theft for practicing medicine without a license. Minehart dismissed six additional counts of that charge Tuesday.

Eight other former co-workers, including Gosnell's wife, Pearl, have pleaded guilty to charges ranging from third-degree murder to racketeering to performing illegal, late-term abortions.

Minehart upheld charges that Gosnell violated Pennsylvania's abortion laws by performing abortions after 24 weeks and failing to counsel women 24 hours before the procedure.

Gosnell had also been charged with five counts of abuse of a corpse, for removing the feet from aborted fetuses and storing them in specimen jars. McMahon argued that his client did so to keep DNA samples, and Minehart agreed to dismiss those counts.