A Lake County, Indiana, judge declared a mistrial Tuesday after it emerged that an Illinois police officer had been allowed to stay on a homicide jury.

Jaylan Mendoza, 23, is charged with murder in the Aug. 20, 2023, death of his father, Delwin McCloud, 42.

His new trial date is Sept. 29. He has pleaded not guilty, and said it was self-defense. He was granted bail in October.

“This is a murder case and the stakes couldn’t be higher,” defense lawyer Lakeisha Murdaugh said via text Tuesday. “When the parties discovered a sworn police officer had been seated on the jury, we had no choice but to act.

“My client has a constitutional right to a fair and impartial jury,” she wrote.

As the juror was questioned Tuesday afternoon alone in court, he said that fellow jurors had already asked him questions on guns, bodycams and trespassing laws.A jury screening form used in Lake County asks candidates if they have served as a police officer, and to list their current job and spouse’s occupation.

Just before the juror was questioned, Murdaugh had asked for a mistrial. She later argued the jury was now “biased,” even if what the officer said was “favorable to the defense.”

Deputy Prosecutor Lindsey Lanham argued they could go forward, saying the gun and bodycam questions were “technical.” Jurors could be given instructions for deliberations on criminal trespassing.

Judge Natalie Bokota disagreed.

“No one caught this error,” she said.

When the jury returned, she told jurors the trial couldn’t continue knowing what the officer had told them. She knew Indiana law prohibited Indiana police officers from serving on juries, she said.

It was a “blunder,” Bokota said, apologizing before sending the jury home.

Court records allege Mendoza shot McCloud eight times on a doorstep. Hammond police responded around 2:40 a.m. to the 3800 block of 176th Place.

Prosecutors and defense lawyers painted two different pictures of what led to the shooting.

Deputy Prosecutor Jacob Brandewie told jurors in opening statements that the shooting was unjustified.

At the heart of the lawyers’ dispute was the security video.

Murdaugh said in court filings that they got a couple of seconds more of footage that showed McCloud lunging at Mendoza before he opened fire.

Brandewie told jurors Tuesday morning it came down to a “good old-fashioned family feud.”

The pair got into an argument hours earlier, he said. McCloud told his son when he got back home, he was kicked out of the basement. Mendoza came back after 1 a.m. with a gun in a “ski mask,” filings show.

McCloud told Mendoza he was knocking on his door like a “crazy person,” Brandewie said.

Where is my stuff, Mendoza replied.

Go get it, his father responded. Then, shots. A forensic pathologist was expected to testify the father had defensive wounds, the prosecutor said.

“People will try to make this messy,” Brandewie said. “He wasn’t justified in doing it.”

Murdaugh’s co-counsel Amishi Sanghvi told jurors Mendoza was “attacked” and trying to “protect” himself. Their client had “physical marks” when he turned himself over to police, she said.

Mendoza was granted bail in October after Murdaugh argued the home security videos could have been “altered” or left with gaps. About an hour passed between the time of the shooting and when one of McCloud’s two live-in girlfriends called 911.

Bodycam footage played Tuesday showed both women and Mendoza’s brother were very emotional.

None saw the shooting. One girlfriend said she heard shots, looked out the window and saw Mendoza running away as they briefly made eye contact.

“Aw, dad,” he appeared to say.

Court records show Mendoza, his brother, McCloud and a woman went to a motorcycle club picnic in Zion, Illinois, that day, court records said. There, they drank for several hours.

McCloud and Mendoza got into a physical fight after arguing about Mendoza’s drinking, court records state. McCloud and the woman left him there and went home. Mendoza’s grandmother drove him back.

Murdaugh wrote in filings that McCloud “threatened to kill” Mendoza that day if he came back home. When Mendoza turned himself in at the Hammond Police Station days later, Mendoza had a “black eye, scratches on his neck, and hole in his shoe” from a bullet — signs of a potential struggle, she argued.

At the bail hearing, she introduced footage provided by Mendoza’s brother, who used his phone to record the security footage. It was a second or two longer and appeared to show McCloud “lunging” at Mendoza’s neck, the lawyer argued.

In filings, prosecutors disputed the characterization.

Lanham and Brandewie countered that the video they had “unfortunately cuts out” on its own. They discounted the brother’s recording, saying it was “not entirely reliable,” since he was “not forthcoming” to police.

Court filings show he didn’t remember much of the day.

Additionally, they argued the shooting was deliberate since Mendoza was on the porch 20 seconds before he opened fire. There was “no physical interaction” between father and son, they wrote.

Prosecutors argued it was “conjecture” that something happened at the picnic to set Mendoza off. He had four hours to cool down, they said, and the black eye wasn’t from a fight on the porch.

Murdaugh rejected their explanation that a “wire shot out” the footage afterwards, since the brother was able to record off the system hours later.

“I’m grateful the error (with the juror) was caught early and I stand by the fight to protect due process at all costs,” the lawyer added Tuesday in a text message.

mcolias @post-trib.com