He is known only as "Baby Boy B," a fetus estimated to be 28 weeks old, found frozen in an altered one-gallon plastic water jug in Dr. Kermit Gosnell's West Philadelphia abortion clinic.

His passing went unnoticed and undocumented, but on Monday, prosecution and defense lawyers struggled to get Philadelphia's chief medical examiner to say whether he was stillborn or killed by Gosnell after being born alive during an abortion.

"Based on the totality of the evidence . . . you cannot testify to anyone that this fetus was born alive?" Gosnell lawyer Jack McMahon asked Medical Examiner Sam Gulino.

"No I cannot," replied Gulino.

Then Assistant District Attorney Edward Cameron flipped around McMahon's question: "Can you think of any reason why the neck was severed if that baby was not born alive?"

Again, Gulino agreed. McMahon tried to salvage his first answer, only to be interrupted by Cameron.

McMahon exploded in anger, but was topped by Common Pleas Court Judge Jeffrey P. Minehart.

"Mr. McMahon, behave yourself!" yelled Minehart. "Act like a lawyer."

McMahon, who once worked with Minehart and Cameron in the District Attorney's Office, sat down, seething, and said nothing more.

The heated exchange capped the first day of the trial's fifth week. It could be the last week of prosecution testimony before the defense case begins.

Gosnell, 72, is charged with seven counts of first-degree murder, seven infants allegedly born alive during abortions and killed by cutting their spinal cords with scissors. If the jury finds him guilty, Gosnell could be sentenced to death.

McMahon has argued that none of the infants were killed, that they were in death throes from the abortion drug, Digoxin, that Gosnell administered earlier.

Gosnell is also charged with one count of third-degree murder in the Nov. 19, 2009 death of Karnamaya Mongar, 41, a Virginia woman allegedly killed by an overdose of Demerol by Gosnell's untrained staff.

Also on trial is Eileen O'Neill, 56, of Phoenixville, an unlicensed medical school graduate who worked in the family practice area of Gosnell's Women's Medical Society. O'Neill is charged with participating in what prosecutors call the operation of a corrupt organization.

Gulino testified about the difficult task of examining the remains of 47 frozen fetuses discovered in Gosnell's clinic during a Feb. 18, 2010, raid by a federal-state prescription drug-abuse task force.

Gulino called it "unprecedented."

"This was something that in 15 to 16 years . . . I had never been asked to do," Gulino testified.

"There was no guidance on how to proceed," Gulino testified, adding that he asked fellow coroners, medical examiners, and forensic pathologists, who were as stumped as he.

Gulino said he finally opened the red and blue plastic bags from Gosnell's freezer, tagged the remains, and slowly let them thaw, to minimize decomposition.

The 47 aborted fetuses ranged in age from 12 weeks - the end of the first trimester - to late second trimester, and included two that looked beyond the 24-week limit for legal abortions in Pennsylvania.

Some were stored in makeshift containers, such as the cut-down plastic water jug or juice containers, Gulino said. Other remains, body parts, were stored in cat and dog food containers.

Former employees testified last week that Gosnell gave different explanations for why he kept up to 30 specimen jars containing fetal feet. He told some the feet were for DNA testing and others they were for medical research.

The reason for the freezer full of fetuses was more mundane. Gosnell was disputing charges by his medical waste disposal firm. He froze the remains and other medical waste awaiting a resolution that never happened.

The jury also got a contrasting view of abortion practice from Charles D. Benjamin, an obstetrician-gynecologist who practices family planning and performs abortions at Einstein Medical Center in Logan and Planned Parenthood's Center City clinic.

Benjamin, who testified he has performed 40,000 abortions over 30 years, said he never performs abortions on women pregnant more than 21 weeks, and those he does are done in a hospital with full medical services available.

Benjamin said he performs abortions up to 17 weeks in a clinic and up to 14 weeks in his personal office.

Benjamin said he has an anesthesiologist or nurse-anesthetist assisting in hospital or clinical abortions. He said he uses a registered nurse to help in office abortions performed with local anesthetics.