In front of a federal grand jury in 2015, Chicago Police Officer Thomas Gaffney said that hours after fellow officer Jason Van Dyke shot and killed Laquan McDonald, he mingled with other officers who’d been at the scene — including Van Dyke — as well as detectives and police union officials at Area Central, talking over the shooting before making his official statement.

Special prosecutors have pointed to this pow-wow, and the fact that the assembled officers submitted reports with matching, allegedly false, information, as proof Gaffney and his co-defendants Joseph Walsh and Det. David March were part of a conspiracy to whitewash the investigation.

As the trial enters its second week, it’s clear that lawyers for the three officers are pinning much of their defense on the argument that officers were following “standard operating procedures”— and not an unwritten code of silence — that were in effect for police department at the time.

They lawyers aren’t wrong, said a former senior official at the Civilian Office of Police Accountability, the city agency that investigates police shootings and misconduct allegations against officers.

“There was just a lot of opportunity for officers to be together, talk about things and get their stories straight (after a shooting),” said the former senior official with the COPA. Officers would “hang out” at area headquarters, chatting, sometimes with union representatives, while waiting for detectives, if not talking informally as a group with detectives, then would submit near-identical reports.

“It was frustrating,” said the official, who asked not to be named.

Police department general orders on officer-involved shootings were changed in 2016 and again in 2017, part of a reform that came after the controversy over how McDonald’s shooting was handled. The latter time, the department added the provision that officers who were involved in a shooting or witnessed one by a fellow officer were to be separated at the scene, as investigators would do with witnesses at a shooting involving only civilians. Officers still get up to 24 hours to make their formal statement to COPA under their contract.

More concerning for the officers on trial is testimony from a fellow officer, Dora Fontaine, that March told her what to put in her reports and added a line to one report that said Fontaine claimed McDonald was moving “as if to attack Van Dyke” when Van Dyke opened fire.

Fontaine testified that was false. If Cook County Judge Domenica Stephenson finds her testimony credible, it is evidence not just of sloppy report writing but of a conspiracy, said Terry Ekl.

Ekl represented bartender Karolina Obrycka in a 2012 lawsuit against Chicago Police Officer Anthony Abbate and the city in which jurors made a finding that there was a “code of silence” among officers.

“I think people are conflating the ‘code of silence’ with a conspiracy,” said Ekl, a former Cook County prosecutor. “I think the two are not necessarily the same thing.”

A conspiracy requires an agreement among two or more people to commit an illegal act — in this case, the obstruction of justice by covering up for Van Dyke. A code of silence is a more pervasive, cultural phenomenon.

“They may not have to have an agreement, they just do it, and everyone knows why,” Ekl said.

Ekl questioned how strong the prosecution’s evidence is in the current case on trial.

“Other than (Fontaine), from what I’ve seen, you don’t have much evidence of an agreement among these officers,” Ekl said.

In addition to the conspiracy charge, March, Gaffney and Walsh each also face individual charges of official misconduct and obstruction of justice, linked to the purportedly false statements in their reports.

Those problematic statements include listing Van Dyke, Gaffney and Walsh as “victims” of an assault by McDonald and descriptions of McDonald both making aggressive moves toward officers when he was shot and trying to get up off the ground as Van Dyke continued firing at him while he was on the pavement. Prosecutors say dashboard camera footage and the statements of civilian eyewitnesses prove that’s not what happened.

Those charges can be proved independent of the conspiracy and may be easier counts for the prosecution, said Renato Mariotti, a former federal prosecutor.

“What that turns on is whether they can say with a straight face that it was all true,” Mariotti said. “I think that is hard to say when you’ve got that video that shows that it is not true.”