OTTAWA -- Lawyers for former Afghanistan hostage Joshua Boyle want a judge to toss out a charge that he misled police -- one of several criminal counts he faces in Ontario court.

Boyle, 36, has pleaded not guilty to offences against his estranged spouse Caitlan Coleman, including assault, sexual assault and unlawful confinement, as well as a charge of misleading Ottawa police in the hours before he was arrested.

The offences are alleged to have occurred in late 2017, after the couple returned to Canada following five years as captives of Taliban-linked extremists who seized them during a backpacking trip to Asia.

In court Tuesday, Boyle's lawyers argued there is insufficient evidence to support the charge that Boyle misled police to believe Coleman was suicidal and missing to divert suspicion from himself.

The Crown has agreed to modify a charge of sexual assault with a weapon, specifically ropes, to simply sexual assault.

Boyle's lawyers argue another charge of sexual assault with ropes should proceed as an allegation of assault with a weapon.

The defence motion to alter the charges, based on testimony to date, is the latest twist in a trial that began in March and likely won't wrap up until next month at the earliest.

Boyle made a frenzied, late-night 911 call on Dec. 30, 2017, to say his wife had run screaming from their Ottawa apartment, threatening to kill herself.

An audio recording of the call, which resulted in a prompt visit from police, was played earlier this year at the trial. The call triggered an investigation that led to Boyle's arrest hours later for allegedly assaulting Coleman.

Despite the bitter cold that night, Coleman fled in her stocking feet and made her way to a downtown hotel where her mother, who lives in the United States, was staying during a holiday visit.

Crown attorney Jason Neubauer said Coleman's recollection indicates she was not suicidal and did not threaten to kill herself.

An Ottawa police sergeant has testified that Coleman provided a detailed statement saying she was trying to get away from her husband because he had threatened to kill her and had assaulted her numerous times.

Lawrence Greenspon, a lawyer for Boyle, said his client did not mislead police. Boyle's expression of concern for Coleman's mental well-being was based on the fact she had a years-long history of harming herself, Greenspon said.

In addition, the Crown has provided no real evidence that Boyle lied to police about his wife going missing that night, Greenspon said.

Coleman has testified that on one occasion Boyle ordered her to strip naked, then used rope to bind her hands behind her back and her feet together on a bed with her face down.

There is disagreement over whether penetration took place but Neubauer argued Monday that even without it, Coleman's sexual integrity was violated during the incident.

Greenspon disagreed, arguing the couple had sometimes engaged in non-sexual rope-tying. Besides, Coleman's memory of the event was so fuzzy that few details can be firmly established, he added.

Judge Peter Doody is expected to rule Wednesday on whether the assault charge in question should be modified and on the allegation of misleading police.