Detectives from two Welsh police forces are investigating a man who allegedly passed himself off as a qualified nurse and worked at a number of hospitals where his duties included administering injections.
The 28-year-old man, whom police declined to name, is said to have gained work as an agency nurse over the past year, and treated patients, administering drugs and injections.
Last week, a man appeared in court at Pontypridd, Glamorgan, charged with assault and obtaining pecuniary advantage by deception. He was remanded in custody.
Police officers from South Wales and Gwent are continuing their investigations with help from the hospitals involved; further charges are expected to be laid.
Officials at the NHS trust covering one of the hospitals involved, the Royal Gwent, at Newport, have carried out a review of procedures and tightened regulations regarding the use of agency nurses.
The man, who was said to have given false information about his qualifications and details of his career, undertook several periods of work at the Royal Gwent and other hospitals in the area, as well as neighbouring South Wales.
However, managers at the Royal Gwent subsequently investigated his background and qualifications, and upon discovering they were false, notified police: the man was later arrested.
Ian Thomas, duty manager at the hospital, which is part of the Glan Hafren Trust, said that since the review, agency staff were now required to produce professional identification each time they worked at any of its establishments. A more detailed inquiry into the use of agency staff was also being conducted, and the results would be passed to the other hospitals in the area, along with any recommendations for changes.