Code of Criminal Procedure, 1973–Sec. 319–Scope–A person not named in the FIR or a person though named in the FIR but has not been charge-sheeted or a person who has been discharged, can be summoned u/s. 319 Cr.P.C., provided from the evidence (maybe on the basis of the evidence collected in the form of statements made in the examination in chief of the witness concerned), it appears that such person can be tried along with the accused already facing trial.
