Editor's note: This article contains graphic descriptions.
Philadelphia (CNN) -- A former medical assistant testified Thursday that she saw more than 10 babies born alive at the West Philadelphia abortion clinic where she worked for a doctor who is now on trial for murder.
Kareema Cross also saw babies or fetal remains in a toilet, a plastic box and jars, she told the court in the trial of Dr. Kermit Gosnell, who is charged with eight counts of murder. He is accused of killing seven babies after allegedly performing illegal late-term abortions and Karnamaya Mongar, 41, who died of an anesthetic overdose during a second-trimester abortion. He has pleaded not guilty.
Gosnell's defense attorney Jack McMahon has maintained that none of the infants was killed; rather, they were already dead because Gosnell had administered the abortion drug Digoxin.
Cross, 28, who stopped working at the clinic in 2009 when she gave birth to a child, reported Gosnell to authorities using the name of a relative, she said.
Cross said Gosnell regularly performed illegal late-term abortions that he routinely recorded as "24.5 weeks." In Pennsylvania, abortions past 24 weeks are illegal unless the health of the mother is at stake.
Cross graphically described witnessing Gosnell cut the necks of several babies while she worked at the clinic. She recalled being present for more than 10 instances in which babies were delivered alive by patients given abortion drugs.
"Were those babies breathing?" Assistant District Attorney Joanne Pescatore asked.
"Yes," Cross replied.
And then there was the time a mother gave birth while sitting on the toilet.
"It was swimming a bit," she said, "basically, trying to get out of the toilet."
She also described a baby so large that his arms and legs hung over the sides a plastic box that resembled a shoe box.
"That was the largest baby I ever saw," she said matter-of-factly, indicating with her hands he was 12 to 18 inches long, before adding that Gosnell commented on his size. "He'd say, 'the baby's big enough to walk to the bus stop,' " she said.
When Cross questioned Gosnell about seeing a baby moving or breathing, he told her what she saw was "not real" and that there were instead involuntary spasms, she said.
"I thought they were breathing; he said they weren't," Cross said.
Jurors were also shown a series of photos Cross took with her digital camera to document the unsavory conditions inside the Women's Medical Society after she become disturbed by the Gosnell's business practices.
Cross admitted to having an abortion herself at a different clinic in 2007 because she was uncomfortable with the conditions at Gosnell's facility.
Jars containing the severed feet of babies lined a shelf. Furniture and equipment was blood-stained, dusty and broken.
Cross pleaded guilty to drug charges in a federal case in which Gosnell is charged with illegally selling prescriptions. She was not charged in the murder trial involving Gosnell.
The clinic was initially raided in 2010 for illegal prescription drug activity, not the doctor's abortion practices. When authorities searched Gosnell's practice, they found bags and bottles holding aborted fetuses scattered throughout the building.
Similar to testimony from other clinic employees, after a few months of working at the Women's Medical Society in August 2005 for $10 an hour, Gosnell had Cross working the ultrasound machine and assisting with abortion procedures, as well as other procedures she was not formally trained to do.
Also on trial is Eileen O'Neill, 56, a medical school graduate who worked as a doctor at Gosnell's clinic. O'Neill, who did not have a medical license, is not charged with performing abortions but with participating in the operation of a "corrupt organization."
If found guilty, Gosnell could be sentenced to death.