He immediately subpoenas all the witnesses, whether previously interrogated by the police or not, who know anything about the matter, and subjects them to a rigorous cross-examination.

Then he sends for the police themselves and cross-examines them.

If it appears that any witnesses have disappeared he instructs his detectives how and where to look for them.

Often this becomes in the end the most important element in the preparation for the trial.

Thus in the Nan Patterson case the search for and ultimate discovery of Mr.and Mrs.Morgan Smith (the sister and brother-in-law of the accused) was one of its most dramatic features.