The defense attorney for a pharmacist accused of second-degree murder has argued that his client was just following his boss’s orders, while a federal prosecutor countered that the pharmacist showed a callous disregard for human life when he shipped out contaminated medicine.

Glenn A. Chin, the supervisory pharmacist said to be involved in the 2012 meningitis outbreak that killed 64 people and sickened more than 700 others throughout the U.S., is now facing federal trial in Boston. The former New England Compounding Center employee is being charged with second-degree murder and conspiracy, as well as other racketeering charges.

Joseph Connolly, a pharmacy technician who worked for the NECC, testified that Chin ignored cleanroom issues such as bugs and cracks in the floor. Connolly also stated that Chin told pharma techs to use expired ingredients when making drugs, and did nothing when a bacitracin shipment came back as non-sterile. He also stated that Chin allowed drugs to be shipped out before contamination test results had come back. When Assistant U.S. Attorney Amanda Strachan asked if Chin had instructed Connolly to do those things, Connolly answered in the affirmative. He also said that Chin could be “insulting and demeaning.”

Read more: Second Pharmacist from Meningitis Outbreak Faces Trial

One of Chin’s attorneys, Robert Sheketoff, fired back at Connolly, suggesting that Connolly’s feelings toward Chin could be influencing his testimony, and asking why Connolly didn’t just resign from his job if he supposedly disliked Chin so much. Sheketoff also reminded Connolly about past statements where he said that Chin was a talented technical pharmacist who worked hard and took his job very seriously, and got Connolly to acknowledge that many of Chin’s directives came from a higher authority — namely, Barry Cadden.

A day prior, a top federal health official took the stand and said that he thought the cause of the deadly fungal meningitis outbreak would be discovered in the Saint Thomas Outpatient Neurosurgical Center in Nashville, where the first case was reported. Dr. Benjamin Park, a CDC official who also testified in Barry Cadden’s trial, said that he thought the outbreak would be limited to the Nashville clinic, but then found out that the outbreak — which stretched to 23 states — could be tracked back to the NECC.

Park was called to the stand after Assistant U.S. Attorney George Varghese told the jury that Chin was responsible for shipping out the contaminated drugs. He described the case of Kentucky Judge Eddie Lovelace, who was injected with methylprednisolone acetate at the Nashville clinic, and who later suffered from a massive stroke caused by deadly fungi that traveled to Lovelace’s brain.

Chin’s lawyers then called for a mistrial, on the grounds that Varghese had misinformed jurors about the standards required of the NECC. U.S. District Judge Richard G. Stearns denied the motion, but then clarified for jurors the source of the standards expected of the NECC.

Chin’s trial comes six months after Barry J. Cadden, former co-owner and president of the New England Compounding Center in Framingham, Mass., was acquitted of murder in March 2017. Cadden was facing 25 counts of second-degree murder. The jury heard nine weeks of testimony and then deliberated for five days before presenting their verdict. Cadden was convicted of racketeering and fraud charges in June 2017, and was sentenced to nine years in prison — he is currently serving his time in low-security federal penitentiary in Pennsylvania.

Read more: Verdict Reached in Meningitis Case

Federal prosecutors have now moved to make Cadden pay almost $74 million in restitution to some of the survivors, and the kin of some of the victims, of the meningitis outbreak.