MELBOURNE (Reuters) - Some of the alleged historical sexual offense charges against Vatican treasurer George Pell will be dropped because one of his accusers is unfit to give evidence, an Australian court heard on Friday.

Vatican treasurer Cardinal George Pell is watched by a security guard and an Australian police officer as he leaves Melbourne Magistrates' Court in Australia, March 19, 2018. AAP/Stefan Postles/via REUTERS

Pell, 76, is the most senior Catholic official to face such charges, the details of which have not been made public.

His lawyers have said at previous administrative hearings he will plead not guilty to all charges. Pell is not required to enter a formal plea unless a magistrate determines there is cause for a full trial.

At the close of the third week of hearings, prosecutor Mark Gibson told the court one accuser was “medically unfit to give evidence”, so charges stemming from his evidence would be withdrawn. No other details were given.

Another charge had been dropped at the beginning of the hearing owing to the death of another of Pell’s accusers.

Families of two accusers told the court on Friday they had only heard of the alleged offences long after they had allegedly occurred, one of them at a pool in regional Victoria state and the other at a church. Those families had never previously seen or heard anything improper involving priests, the court heard.

Pell’s lawyer, Robert Richter, accused the sister of one of the complainants of lying in her statement to police, which said her brother had told her Pell was the alleged offender.

“That’s a story that was made up by you about naming George Pell,” Richter said.

The man’s sister replied: “I would say that’s incorrect.”

Her name cannot be disclosed because it would identify one of the accusers.

Richter pressed her on why she had not asked her brother more questions about the alleged incident between the time he brought it up and when she gave a statement to police two or three years later.

“As I said before, it was a clearly painful and embarrassing thing for (my brother) and I didn’t want to probe into what was going on with him,” she said.

The committal hearing is scheduled to end next Thursday.

Pell is on a leave of absence from his Vatican role as Pope Francis’ economy minister, which he started in 2014. The pontiff has said he will not comment on the case until it is over.