"Turning" this type of "evidence" means giving testimony to implicate accomplices
Turning state's evidence plays an important role in the criminal 
justice ... involvement but once he turned state's evidence he implicated former 
Sigma TV... [DOC] [TLE] House of Lords - R v Davis (Appellant) (On appeal from the Court of ... [PAR] The evidence of a detective officer quoted by the Court of Appeal in paragraph 9 
of ... potential witnesses, who are reluctant to give evidence against a fellow gang 
... by the Scottish courts and is often best detected by implication from other rules.