Published: Oct 17, 2012 6:10 PM EDT
Updated: Oct 17, 2012 10:52 PM EDT

COLLIER COUNTY, Fla.- Another doctor called to testify today in the case against Bonita Springs Dr. Zannos Grekos says he was concerned when he learned about the procedure Grekos performed.

The four day hearing before an administrative law judge focuses on the death of a 69-year-old Grekos patient in 2010.

Dr. Grekos infused the bone marrow into the woman's brain to help cure a walking disability and nerve problem caused by chemotherapy.

But hours after the procedure, the woman had a bad reaction and fell at her home, hitting her head on the couch. She was taken to the hospital.

The medical examiner said she had a stroke because of the infusion and that ultimately lead to her death.

Dr. Richard Roland, who saw the woman that next morning at the hospital, says he was shocked when he spoke to Dr. Grekos and found out about the procedure he performed.

"I was shocked, said you did what? He said 'we've had good luck with the procedure.'"

Dr. Roland said it led him to do something he hasn't done before, call the medical examiner before a patient passes away. "I contacted the medical examiner because of my concern that this situation..was more than just medical or civil malpractice, I had concerns that this was criminal."

The defense called its first witness this afternoon, a biomedical engineering expert, who testified that the stem cell treatment does have scientific value and was an appropriate treatment.

The hearing continues Thursday and Friday. There is still no word whether Dr. Grekos himself will testify.