David Lopez-Zuniga, an air-conditioner installer, had just left his mobile home for his typical predawn commute when he noticed an SUV’s headlights closely trailing his small cargo truck.

Within seconds, the SUV swerved alongside the passenger’s side, striking the truck and forcing Lopez-Zuniga to the side of a highway. There, he said, the SUV’s driver feigned an injury before ordering Lopez-Zuniga to the ground at gunpoint.

“I was very scared,” Lopez-Zuniga, said in an interview with The Washington Post. “I didn’t know who this person was.”

As it turned out, the incident was the extraordinary culmination of a misguided undercover surveillance operation — financed by a conservative nonprofit group and carried out by private investigators — that sought to uncover a massive election fraud scheme before the November election.

Police said that Lopez-Zuniga, 39, was the victim of a bogus conspiracy theory alleging he was involved in transporting 750,000 mail-in ballots fraudulently signed by Hispanic children whose fingerprints could not be traced.

After an investigation into the Oct. 19 incident, authorities last week charged the SUV’s driver — who is a private investigator and former Houston police captain — with assault with a deadly weapon. The private investigator, 63-year-old Mark A. Aguirre, pleaded not guilty on Friday. His lawyer says the case is politically motivated.

Lopez-Zuniga allowed police to search his home, a shed behind his house and his truck, where they found no evidence of voter fraud, the police affidavit says. What they found in the truck instead: air conditioning repair equipment.

Since Nov. 4, President Trump has repeatedly claimed his election loss as a result of massive fraud. The following is a roundup of his claims. (The Washington Post)

The episode illustrates the extreme and sometimes dangerous tactics that a set of conservative groups have employed in an effort to substantiate President Trump’s unproven allegations of widespread voting fraud in the election. Theories about truckloads of missing mail-in ballots, manipulated voting machines and illegal mail-in ballot collections have abounded in far-right circles, despite a lack of credible evidence, leading to threats of violence against election workers and officials.

Many of the fraud allegations have come in the form of lawsuits that have been rejected by state and federal judges across the country.

The overall effort in Houston stands out because it relied on an expensive, around-the-clock surveillance operation that, for reasons so far unknown publicly, targeted a civilian — authorities called him “an innocent and ordinary air conditioner repairman” — with no apparent role in government or election administration. The operation was also financed by a newly formed nonprofit group run by a well-known GOP donor in Texas and prominent former party officials in Harris County, the state’s most populous county, corporation records show.

The nonprofit group, the Liberty Center for God and Country, paid 20 private investigators close to $300,000 to conduct a six-week probe of alleged illegal ballot retrievals in Houston leading up to the election, the group has said. None of its allegations of fraud have been substantiated.

The group’s president, Steven F. Hotze, did not respond to an interview request.

Aguirre declined to say why the operation focused on Lopez-Zuniga, who lives in a modest mobile-home park with his wife and daughter on the south side of the city.

“I’m not trying my case in the paper,” Aguirre, who was released on $30,000 bail, told The Post in a brief phone interview on Dec. 16. “I don’t care about public opinion. I’m trying my case against these corrupt sons of [expletives].”

The origins of Aguirre’s election fraud investigation date to the formation of the Liberty Center for God and Country in late August.

The nonprofit was created by Hotze, a natural health doctor and megadonor to Texas conservatives, who has taken a leading role in election litigation in the state. Hotze filed a series of lawsuits before November’s presidential election seeking to limit mail-in voting and dismiss ballots submitted via drive-through voting sites.

Most of Hotze’s recent election lawsuits were unsuccessful. However, the Texas Supreme Court in one case prohibited Harris County from sending out applications for mail-in ballots to all registered voters.

Hotze also has spearheaded anti-gay rights campaigns, claiming in 2015 that the legalization of same-sex marriage would lead schools to teaching kindergartners to “practice sodomy.”

Hotze’s nonprofit group was created “for the purpose of ensuring election integrity primarily,” said Jared Woodfill, Hotze’s personal lawyer and the former executive director of the Harris County Republican Party, the county that includes Houston. Woodfill is listed on state incorporation records as a director of the nonprofit group, along with Jeffrey Yates, the former longtime chairman of the county’s Republican Party. Yates did not respond to phone messages.

“The socialist Democrat leadership in Harris County has developed a massive ballot by mail vote harvesting scheme to steal the general election,” a now-deleted fundraising page for the group alleged. “We are working with a group of private investigators who have uncovered this massive election fraud scheme.”

The group raised nearly $70,000 through a GoFundMe page from Oct. 10 through last week. Hotze has said publicly that he donated $75,000 to the probe and that an unnamed individual had donated another $125,000.

Hotze turned to Aguirre to assemble a team of 20 private investigators, according to Aguirre’s attorney, Terry Yates, who is not related to Jeffrey Yates.

“Mark would say he’s the guy who was in charge,” Terry Yates told The Post.

Before becoming an investigator, Aguirre’s career in law enforcement ended in controversy.

The former Houston police captain was fired in 2003, according to news reports, after he ordered the mass arrest of 300 people in the parking lot of a retail store, some of them families on shopping trips, as part of a crackdown on drag-racing. The roundup led to multiple lawsuits against the city, and the city paid at least $840,000 to settle some of the suits, according to the reports.

Aguirre, a 23-year veteran of the department, also was charged criminally with official oppression, a state statute that covers abuses of power by public officials. A jury acquitted him, and after that Aguirre appealed his firing and was allowed to resign before he launched his career as a licensed private investigator, his attorney said.

In September, Aguirre wrote an affidavit for a lawsuit brought by Hotze and the Harris County GOP before the Texas Supreme Court seeking to curtail early and mail-in voting. The affidavit alleged Democrats had devised a scheme to submit as many as 700,000 fraudulent ballots in Harris County. The Texas Supreme Court dismissed the lawsuit on Oct. 7.

Nevertheless, law enforcement officials in Harris County began looking into the claims in the affidavit. The affidavit did not mention Lopez-Zuniga, but described what it contended was a broader ballot-harvesting effort directed by local Democratic officials.

Four investigators from the Harris County Precinct 1 Constable’s Office, which is responsible for investigating voter integrity issues, were assigned to the investigation, an official said.

“We looked into the allegations,” said Constable Alan Rosen, who said investigators conducted interviews with various people but got no cooperation from Aguirre and other private investigators. “We wanted to investigate their side of the story and they wouldn’t talk to us.”

“No proof was ever substantiated,” according to Rosen.

As the Nov. 3 Election Day neared, Aguirre and other unidentified private investigators began to monitor Lopez-Zuniga more closely, court records show. By mid-October, they had devised a plan to carry out extensive monitoring that kept eyes on the air conditioning repairman day and night, court records show.

Beginning around Oct. 15, the investigators started “24 hour surveillance” on Lopez-Zuniga’s mobile home, a police affidavit states. They set up a “command post” nearby, renting two hotel rooms for four days in a Marriott hotel, according to the affidavit. As they watched Lopez-Zuniga, Aguirre unsuccessfully tried to convince law enforcement authorities at the state level that he was on to something big, according to several law enforcement agencies and court records.

On Oct. 16, Aguirre called a member of the state attorney general’s election task force, Lt. Wayne Rubio, to request that Rubio order a traffic stop of Lopez-Zuniga’s vehicle, court records show. Rubio declined. Aguirre “seemed upset that the Department of Public Safety could not stop and detain an individual based solely on [Aguirre]’s uncorroborated accusations,” Rubio later told police, according to the affidavit.

Aguirre told Rubio that he would make the traffic stop and execute a “citizen’s arrest,” the affidavit states. Rubio did not respond to interview requests, and the Attorney General’s Office declined to comment.

Aguirre also contacted Jason Taylor, a regional director at a separate statewide law enforcement agency — the Texas Department of Public Safety — the agency said in a statement to The Post. That contact came a day before Aguirre is accused of ramming Lopez-Zuniga.

“Mr. Aguirre brought up the allegations of election fraud during a phone call on Oct. 18, 2020, with the Texas Department of Public Safety (DPS) Regional Director,” a spokesman wrote. “Based on that call, the matter was then discussed with the (DPS) Texas Ranger Division. The decision was then made to refer Mr. Aguirre to the Office of the Texas Attorney General.”

Aguirre later told police he was frustrated that he had “not received any help” from law enforcement agencies, according to the police affidavit.

On the morning of Oct. 19, Lopez-Zuniga left his home at around 5:15 a.m., hopping into his box truck with a lunch his wife had prepared, he said. Only minutes into his drive, he saw the SUV, trailing him closely as he drove at about 45 mph.

“I was driving like I normally do, and I see a car behind me,” Lopez-Zuniga said in Spanish during a brief interview outside his home. “He was swerving. I thought he was drunk.”

Lopez-Zuniga slowed to let the SUV pass, but instead it careened into his truck, he said.

Aguirre exited his SUV with his hand in his jacket, leading Lopez-Zuniga to believe he was injured, the air-conditioner technician said.

“So I got close to him to help him, and that’s when he pulled the gun out and pointed it at me,” Lopez-Zuniga said. Aguirre unlocked the safety on his gun, ordered Lopez-Zuniga to the ground and pinned him with a knee on his back, Lopez-Zuniga said.

Soon, two other men arrived in a separate car, Lopez-Zuniga said. One, he said, inspected his truck. The truck was then driven to a nearby location and abandoned, according to the police affidavit.

A Houston police officer who was driving by the scene “saw the incident in progress,” according to the affidavit, which gives the following account:

Aguirre at first admitted to following Lopez-Zuniga and said that he’d been surveilling the repairman for the previous four days. He later changed his story and claimed not to be involved in the surveillance operation and refused to name other private investigators working with him. But he insisted that Lopez-Zuniga’s truck had 750,000 fraudulent ballots in it and that Lopez-Zuniga was “using Hispanic children to sign the ballots because the children’s fingerprints would not appear in any databases,” the affidavit states.

“I just hope you’re a patriot,” Aguirre allegedly told the Houston police officer, before taking him to Lopez-Zuniga’s neighborhood where Aguirre pointed out his surveillance spot.

Police later reviewed grand jury subpoena records from Aguirre’s bank, the police affidavit states, and saw wire transfers of nearly $270,000 to his account from the Liberty Center for God and Country with payments of $25,000 each wired on Sept. 22 and Oct. 9, and $211,400 deposited the day after the alleged assault.

Houston police declined an interview request and said they would not answer specific questions about the case because the department’s investigation is ongoing.

The Harris County District Attorney’s Office, which charged Aguirre after a grand jury indictment, also declined to answer questions. “This is an active, ongoing investigation,” spokesman Michael Kolenc wrote in an email.

Terry Yates, Aguirre’s attorney, said on Wednesday that his client was not cooperating with police.

The attorney called the charge “a political prosecution” and questioned why Aguirre was charged nearly two months later rather than by an officer at the scene.

In a news conference on Wednesday afternoon, Hotze called the charges against Aguirre “bogus.”

Hotze was asked if he was concerned about his group’s financing of the bungled surveillance operation. “We are very proud of what we’ve done,” Hotze told reporters. He said Aguirre was “highly recommended” and “a very good investigator.”

Hotze said GOP organizations were not directly involved in funding or organizing the surveillance operation, and he faulted them for leaving him “to do all the work.”

He also claimed, without elaboration, that the investigation had blocked a Democratic fraud scheme that would have otherwise flipped Texas to Democrat Joe Biden. Hotze did not respond to interview requests through his attorney.

The botched investigation has not shaken the resolve of some of the donors to Hotze’s nonprofit. Businessman Steve Kerns, who gave $5,000 to the Liberty Center in October, said he didn’t know the details of the Aguirre incident but felt confident his donation was a good investment.

“And I know hundreds of other people who would say the same,” he said.

(This article has been updated to correct the spelling of the name of Steve Kerns.)

Hoffman reported from Houston. Brittney Martin in Houston and Alice Crites contributed to this report.