Missing cell phone and text messages that the Crown says were deleted were the focus of testimony at the sexual assault trial of former Bridgewater police chief John Collyer.

Sgt. Gordon Vail was the main witness to take the stand in a Bridgewater courtroom on Wednesday.

Vail is an investigator with Nova Scotia's Serious Incident Response Team (SIRT). He was in charge of the investigation into Collyer.

Collyer is a former police chief, charged with sexual assault and sexual exploitation in 2016, of a then-17-year-old girl.

He's pleaded not guilty to both and elected trial by judge only.

On Wednesday, Vail told the court that a cell phone, issued to Collyer, from the Bridgewater Police Service, was reported missing in August 2016 days after the allegations came to light.

That cellphone, considered a critical piece of evidence, was never found.

Vail testified that it was the one that they believed had been used to send the Facebook messages, so, it would have been an item that could have provided them with corroborating evidence. The fact that it was reported as being lost means that evidence obviously, not available, said Crown Attorney Roland Levesque.

Vail testified he saw screen shots of Facebook messages deemed inappropriate by the complainant’s mother.

He said he requested data from Facebook, who indicated that between April 2015 and August 2016, there were 596 messages between Collyer's account and the teen.

Vail said all of the correspondence was deleted from the complainant’s account and only 60 interactions were left on Collyer's -- none of which Vail said were considered inappropriate.

“It turned out to show a situation where the vast majority of the correspondence between Mr. Collyer and the complainant has been erased or deleted,” Levesque said. “We view that as an important element in regards to the charges.”

Lawyers are paying close attention to the timeline.

Only six days were set aside for the trial and things are behind schedule.

Under the Jordan decision, if you have a trial before the Supreme Court in relation to an indictable offence, you have to complete the trial within 30 months because the accused has a Charter right to a trial within a reasonable period of time.

A deadline that in this case is fast approaching.

“So, the court has set a ceiling, which means that when we're in court, involved in a trial before supreme court, we have to conclude it before 30 months and in this particular instance here, that deadline is Nov. 3rd of this year,” Levesque said.

It's expected the complainant will take the stand sometime this week.

With files from CTV Atlantic’s Natasha Pace.