Time is running out for federal authorities to bring charges against Chicago Police officers who allegedly covered-up for Jason Van Dyke the night he shot and killed Laquan McDonald.

The shooting occurred October 20, 2014. Starting that night and continuing through the following morning, police officers submitted a wave of false reports about the moments before Van Dyke fired 16 shots into the teenager.

That makes this Sunday and Monday key dates in any timeline for federal authorities to bring charges about the alleged cover-up.

“Any statement that obstructs justice — that makes the FBI’s investigation harder — they could bring charges five years after that statement,” said Roy L. Austin Jr., a former federal prosecutor who supervised the criminal section of the U.S. Justice Department’s Civil Rights Division.

Three officers had been criminally charged by Cook County prosecutors with engaging in a cover-up for Van Dyke but the officers in January were found not-guilty.

The verdict pleased Kevin Graham, president of the Fraternal Order of Police lodge that represents rank-and-file Chicago officers.

“It is cases like this, where officers haven’t done anything wrong, that [show] there was no conspiracy,” Graham said outside the courtroom. “Let me make this very clear. There was no code of silence.”

But federal authorities could decide that the acquittals were a failure of the state courts and bring additional charges.

Authorities could also bring federal charges against Van Dyke for the shooting itself — even after his conviction in state court of second-degree murder and aggravated battery. He was sentenced to 81 months in prison but Van Dyke only has to serve half that time and is eligible for release in early 2022. Additional federal charges in the shooting would have no statute of limitations because Van Dyke’s actions resulted in death.

“They’ve certainly had plenty of time to make a decision,” said Sergio Acosta, a former federal prosecutor who oversaw criminal civil-rights cases in the U.S. attorney’s office for seven years. “My guess is that after Van Dyke was sentenced — and the sentence was upheld — that they did undertake some sort of review.”

On several occasions, Acosta pointed out, the feds have prosecuted police officers after a sentencing by a state court that was deemed too light.

Acosta oversaw a case focused on Chicago officer William Cozzi, who was recorded on videotape in 2005 repeatedly beating a man who was shackled in a wheelchair. A Cook County prosecution led to Cozzi pleading guilty to misdemeanor battery and receiving a sentence of 18 months’ probation.

“We ran it through the process internally and made a decision to prosecute him federally,” Acosta said of the civil-rights charges his office brought.

Cozzi, who pleaded guilty, was sentenced in 2009 to 40 months in federal prison.

During her mayoral campaign, former federal prosecutor Lori Lightfoot implored the feds to take action.

“The U.S. attorney’s office and the FBI actually took the lead on this case and never brought any charges,” Lightfoot said in a WBEZ interview, referring to the first years after the shooting. “They need to reopen the grand-jury investigation. And the chips will fall where they may, but that needs to happen.”

After Monday, the feds would still be able to charge officers in the alleged cover-up but the focus would have to be statements that took place no more than five years previously — such as testimony to the federal and state grand juries that investigated the officers.

John Lausch, the U.S. attorney in Chicago, declined to comment on whether his office might yet bring charges regarding the shooting or alleged cover-up. The U.S. Justice Department’s press office in Washington did not respond to questions.

Austin called any federal prosecution unlikely during the Trump administration, “which has shown that it is going to bend over backward to stand with law enforcement even when law enforcement does the wrong thing.”

As proof, Austin pointed to a July announcement that Attorney General William P. Barr had decided there would be no federal charges against police officers in the death of Eric Garner, the 43-year-old man whose 2014 takedown by New York City cops led to the Black Lives Matter rallying cry, “I can’t breathe.”

Chip Mitchell reports out of WBEZ’s West Side studio about policing. Follow him at @ChipMitchell1.