Cleveland Police issued 38 “threat to life” notices over three years.
The Osman Warning letters are issued by officers if they become aware of a real or immediate threat to the life of a person.
Figures for forces across the country have been released under Freedom of Information laws, with Cleveland Police sending nine warnings in 2014.
Eight were sent in 2013 - but Hartlepool Police did not record the number of warnings. In 2012, there were 21 warnings - though Stockton did not collate information that year.
Detective Sergeant Richard Baker: “If Cleveland Police receives intelligence to suggest someone’s welfare or their life is at risk, then a thorough review is carried out to consider the veracity of all information received.
“If we believe there is a high risk to a person then we inform them through a risk of harm warning and we then carry out risk assessments with that person to ensure all appropriate measures are in place for their welfare and safety.”
In Durham, there were 9 warnings issued last year, 22 in 2013 and 10 in 2012.
Recipients of the warnings included a boy and a girl under the age of 18 (2012) and a man over 60 in 2013.
Detective Superintendent Lee Johnson said his officers deal with threats being made on a day to day basis – with a minority of them being assessed as genuine.
He added: “Determining which threat is real and immediate, genuine or insincere is a critical aspect of daily policing both for officers in direct contact with the public, as well as managers and senior managers within the organisation.”
Across the UK, police forces have sent out more than 1,900 of the notices since they launched in 2012.