The doctor who told police a father may have murdered his two sons on the basis of a television documentary says he still holds that view.
Sally Clark was cleared of murdering her two sons
Professor David Southall contacted police to voice concerns about Steve Clark, whose wife Sally was jailed and then cleared of murdering their sons.
He told the General Medical Council that he still believed that Mr Clark may have killed the children.
The GMC is considering whether he should be struck off.
Sally Clark was convicted in 1999 of murdering her two sons Christopher and Harry.
However, her conviction was quashed when new medical evidence showing the babies died of natural causes was accepted by a second appeal hearing in January, 2003.
The GMC case centres around an interview with Mr Clark on Channel 4's Dispatches programme broadcast in April 2000.
In his interview, Mr Clark described how the couple's first baby Christopher had suffered a nosebleed just 10 days before he died in December 1996.
Professor Southall told the GMC on Thursday that he had been "stunned" by Mr Clark's interview.
He said Mr Clark's account of what had happened suggested that the baby may have been suffocated intentionally.
Speaking on Friday, Professor Southall said he also believed that Mr Clark had killed the couple's other son.
"I felt the information I had about the nose bleed indicated that Steve Clark had done it and that the subsequent two deaths had been done by Mr Clark."
Asked if he still believed that Mr Clark killed his two children, Professor Southall replied "yes".
Earlier, Professor Southall defended his decision to contact police after watching the
"If I had not done what I did, I think that would have been a hidden abuse of my professional responsibility."
He said his motivation for contacting the police was out of concern for the couple's third child.
"The main overriding motivation was the fact that there was a third child in the family living with a person who I was very concerned might harm him."
He also defended his decision to form an opinion on the case on the basis of a documentary.
"It's not astonishing to me, it's based on many years of investigating this sort of thing medically."
Mr Clark, who lodged a complaint against the professor, told the GMC on Tuesday that he thought the allegations against him were a "sick joke".
Professor Southall, based at North Staffordshire Hospital in Stoke, is one of Britain's leading experts on Munchausen's Syndrome By Proxy, a condition which apparently drives parents to harm their own children in order to win attention.
The hearing was adjourned until Monday.