A judge has ruled that former Roman Catholic Cardinal Theodore McCarrick is not competent to stand trial.

The charges accusing the 93-year-old of sexually assaulting a teenage boy in Massachusetts have been dismissed.

A psychologist testified that McCarrick was unfit to participate with his lawyers in his own defence.

The once-powerful American prelate had faced charges that he abused the teenage boy at a wedding reception in 1974.

McCarrick, the ex-archbishop of Washington DC, was defrocked in 2019 after an internal Vatican investigation determined he sexually molested adults as well as children.

The McCarrick scandal created a crisis of credibility for the church, primarily because there was evidence Vatican and US church leaders knew he slept with seminarians but turned a blind eye as McCarrick rose to the top of the US church as an adept fundraiser who advised three popes.

During Wednesday’s hearing, Dr. Kerry Nelligan, a psychologist hired by the prosecution, said she found significant deficits in McCarrick’s memory during two interviews in June and he was often unable to recall what they had discussed from one hour to the next. As with any form of dementia, she said, there are no medications that could improve the symptoms.

McCarrick has always maintained his innocence.