A surety at a bail hearing may be asked about the offence

While s. 518(1)(b) of the Criminal Code insulates the accused from being cross-examined about the offence, no such protection is afforded to sureties or others.

See Ayanah, [2004] O.J. No. 5189 (OCJ, Opalinski J.):

Ruling on show cause hearing. The accused, Ayanah, had applied for judicial interim release. The Crown attempted to ask certain questions of the surety relating to the circumstances of the offence.

HELD: The court allowed the Crown to question the surety provided that the questions were trustworthy and credible.

Thanks to Yossi Schochet for this