Catia Moreau, who lives a few doors down from the building where Trudeau and her partner arrested a man after putting him in a headlock, said in the aftermath of the incident, a group of officers huddled underneath her balcony to discuss how to write up what had happened.
Moreau said she clearly overheard Trudeau loudly tell one police officer to change his notes, because "if it ends up in court, I don't want to be caught."
"When I recalled all of the events, I told myself that police really had each other's backs no matter what the behaviour," said Moreau. "We tell ourselves this could go further and that they have each other's backs to the point of changing police reports to make sure things go in their favour in court and against the people arrested."
Police have declined a request for comment from the French-language service of CBC, Radio-Canada, but said they would be meeting with Moreau in the coming days to get her version of the events.
Trudeau has been suspended while police investigate the latest complaint against her.
If what Moreau said is true, Trudeau and other police officers could face serious consequences and even see their badges revoked.
Mathias Tellier, a former provincial police officer, said "if there is proof that police officers submitted reports that were not true to the facts, they could face accusations."
"I think maybe it's a natural for anybody that thinks they got themselves into trouble to try and not bear the consequences. But, she was then going into very dangerous roads because the crime of obstructing justice has a very wide definition," said former public security minister Serge Ménard. "It is not very clear from the testimony that we saw on Radio-Canada what she said but it really looks like it, I am sure the investigators will look into it and the directors of public prosecutions will probably consider – if that crime was committed – [dismissal]."
New video shows Trudeau yelling at witness
On Saturday, a new video surfaced on YouTube taken by a witness outside the Papineau Street apartment where Trudeau and her partner carried out the now infamous arrest.
In the video, Officer 728 can be seen holding the man down at the bottom of the staircase and yelling at him.
Another witness who was capturing the incident on her phone was ordered to "leave now, right now," by Trudeau.
The second witness is then overheard on the latest YouTube video saying she thought she "should call the police" since she was concerned by Trudeau's behaviour.
On Thursday, further conversations which appear to have been unwittingly captured on a cellphone revealed the officer calling the people involved in the arrest "rats," and "assholes," among other expletives, on a call to her supervisor.
The person who posted the video added a note saying the witness that was ordered to leave by Trudeau was one of four people later charged with obstruction of justice.
Altercation started with open beer
The man seen in a chokehold in the video has alleged that Trudeau confronted him and asked for identification while he was holding a door open for one of his friends who was loading audio equipment into a building that evening.
Rudy Orchietti said he had a beer in his hand and asked Trudeau why she wanted to see his I.D.
He claims Trudeau pushed him, kneed him in the back and asked if he wanted to spend the night in jail.
"[Trudeau] was on the way to strangle me," Lavoie said. "The further down we got, the more she was choking me and the more I was convinced she was going to kill me."
Montreal police chief apologizes
Marc Parent, Montreal's police chief, apologized for Trudeau's actions on Thursday.
Trudeau, who was initially disarmed and placed on desk duty after police administrators saw videos broadcast on Radio-Canada, was suspended from duty pending an internal investigation.
"I would like to apologize to the citizens on my behalf and on behalf of the employees of the SPVM because what we heard yesterday by the officer on TV and on social media was unacceptable," Parent said.
"It's not what we want to hear from our police officers. It's not based on our values."
Trudeau faced multiple complaints
Trudeau faced at least three other complaints of misconduct since 1996.
In the spring, her badge number, 728, quickly made its way through social media platforms after a video posted to YouTube showed an officer with that badge number pepper-spraying seemingly peaceful protesters during a student march.