The action has been taken after he was found guilty of intentionally misleading the London Borough of Merton.
Dean Percival is found to have intentionally misled a public authority when providing a character reference for a former officer.
He was approached by bosses at Merton for the reference in April 20-23.
But the officer concerned had been dismissed from the force for gross misconduct the previous year.
DI Percival denied intentionally misleading Merton and said that his actions did not amount to misconduct.
He had been a serving police officer with BTP since 2004.
