R. v. Stevenson, 2024 SKCA 40, April 11, 2024, at paragraph 32:

In a judge-alone trial this means when the Crown’s case relies on the testimony of a witness or witnesses who fit into the Vetrovec category, the judge must be alert to the potential credibility and reliability problems that such witnesses may present and must carefully examine their evidence for confirmation before relying on it (R v Omer, 2022 SKCA 147at para 22; Wolff at para 61). But Vetrovec does not stand for the proposition that a trier of fact necessarily commits a legal error by relying on the testimony of a witness who has a lengthy criminal record, a history of dishonest or discreditable conduct, a self-interested motive to testify favourably for the Crown, or some combination of these factors. Nor does the need to carefully examine an unsavoury witness’s testimony for confirmation mean that corroboration is a legal requirement that must be present before that witness’s evidence can be accepted. In Khela, the Supreme Court recognized that “where the guilt of the accused is made to rest exclusively or substantially on the testimony of a single witness of doubtful credit or veracity, the danger of a wrongful conviction is particularly acute”, but also confirmed that “[t]he evidence of a single witness is nonetheless sufficient in Canada to support a conviction for any offence other than treason, perjury or procuring a feigned marriage” (at para 2). The Court further observed that the foundational elements of the Vetrovec caution are designed to ensure that triers of fact do not lightly accept unsupported assertions made by disreputable or unsavoury witnesses, and that they “should look for evidence from another source tending to show that the untrustworthy witness is telling the truth as to the guilt of the accused” before doing so. However, the Court also noted that a trier of fact is entitled to convict on unconfirmed evidence of this sort “if satisfied that the evidence is true” (Khela at para 37; see also: R v Kehler, 2004 SCC 11 at paras 17–19, [2004] 1 SCR 328).