On how many occasions have the DFID used Private Investigators (or Private Detectives of Tracing Agent) to obtain information in the last 5 years

Full request and response

1.On how many occasions have the Department for International Development used Private Investigators (or Private Detectives of Tracing Agent) to obtain information in the last 5 years.  Please give information by year.
2.How much have you spent per year on Private Investigators (or Private Detectives of Tracing Agent) in the last 5 years
3.What services do you use Private Investigators (or Private Detectives of Tracing Agent) for?
4.What are the names of the Private Investigators (or Private Detectives of Tracing Agent) you use?
I can confirm that DFID has no record of using private investigators, private detectives or tracing agents in the past 5 years