Medical jurisprudence -- types of examination in court:
$\text{Examination in chief}$ (direct examination): The witness is questioned by the lawyer who summoned them. Leading questions NOT permitted (Indian Evidence Act, Section 143).
$\text{Cross examination}$: The opposing counsel questions the witness. Leading questions ARE permitted. The goal is to test the veracity, credibility and memory of the witness and elicit admissions favourable to the questioner's client.
$\text{Re-examination}$ (redirect): After cross, the original lawyer may clarify; no leading questions.
The question "Were you present when A killed B?" presupposes A's guilt and directs the witness toward a specific answer -- this is the definition of a leading question, permissible only in cross examination.
\[\boxed{\text{Cross examination}}\]