Following the news that Hertfordshire Police had received reports of physical and sexual abuse of child patients at the former Hill End Hospital Adolescent Unit in St Albans, the officer leading the investigation has said that "sometimes you just get a feeling" about things and need to probe further.
The force went public on Thursday with its investigation into the alleged abuse at the unit between 1969 and 1995.
Assistant Chief Constable Bill Jephson said the investigation had been running for sometime, but it wasn't a particular report that set it off.
He said information had come from a number of different sources, so they began to review the information they had and look at records from the 1970s and 1980s. It was then decided that it "needed a proper look".
"It was prompted by a number of bits of intelligence so we have gone back and looked at if we joined the dots," he said.
"Sometimes you just get a feeling that we need to lift the lid and have a proper look at it with a dedicated team."
Those who believe they have been a victim of this type of abuse are encouraged to contact the police. There is a special online reporting option on the force's Operation Meadow web pages.
No arrests have been made but Mr Jephson said if anyone was found to be currently at risk, mechanisms were in place to respond.
Hill End Hospital no longer exists and a housing estate was built on the site in Hertfordshire.