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The park ranger spotted him kneeling in the bushes by the 112-year-old Confederate statue, explosives in hand.

Was he trying to harm the statue? she asked.

Yes, he said. He didn't like the guy.

The late-night confrontation at the statue of Confederate Lt. Dick Dowling — detailed in court records by a federal agent — led to the arrest of 25-year-old Andrew Schneck, setting off a two-day operation by law enforcement that forced the evacuation of the tony Rice University neighborhood where Schneck lives with his parents.

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Bomb squad experts detonated a cache of high-powered explosives found on the property Monday afternoon as residents waited to return to their homes.

The arrest marked the latest chapter in a growing fight over Confederate statues that has sparked protests across the country, punctuated by a deadly clash between white supremacists and counter-protesters Aug. 12 in Charlottesville, Virginia.

Schneck, charged Monday with attempting to maliciously damage or destroy property, was ordered into federal custody pending a court hearing later this week. If convicted, he could face up to 40 years in prison and a $250,000 fine.

It is the second time Schneck has run afoul of federal law enforcement. He was convicted in 2014 of storing explosives at another of his parents' properties and sentenced to five years probation, but was released early last year.

Lawyers for Schneck offered few details about the case.

"This is an evolving situation, with an ongoing investigation," said Philip Hilder, who is representing Schneck and who represented him in the previous case. "It would be premature to comment at this time since we have not seen the evidence."

The white marble statue of Dowling, an Irish immigrant who lived in Houston and fought for the Confederacy, was erected in 1905 to honor rebel soldiers who died at the Battle of Sabine Pass. A street named for Dowling was changed earlier this year to Emancipation Avenue.

Schneck's arrest about 11 p.m. Saturday followed a day of protests and counter-protests over another controversial statue, the Spirit of the Confederacy, in Sam Houston Park. The "Destroy the Confederacy" protest drew hundreds but ended without incident.

Park Ranger Tamara Curtis, who was not allowed to speak to the media Monday, found Schneck near the base of the Dowling statue with two boxes filled with a homemade detonator, a timer, wiring, a battery, a bottle of nitroglycerin and an explosive organic compound known as HMTD, hexamethylene triperoxide diamine, according to the sworn statement by Federal Bureau of Investigations Special Agent Patrick Hutchinson.

After being confronted, he tried to drink some of the liquid explosives but "immediately spit the liquid on the ground ... then proceeded to pour the contents of the bottle on the ground next to him," according to the statement.

"Nitroclycerin is highly dangerous to transport or use," Hutchinson wrote. "ln its undiluted form, it is one of the world's most powerful explosives."

Schneck told law enforcement he had other chemicals at his home on Albans Road, sending a swarm of local and federal agents to the tree-lined street just north of Rice University.

The searches Monday followed an all-night "enforcement operation" led by the FBI.

Deron Ogletree, an assistant special-agent-in-charge in the FBI's Houston office, said experts came in from the national training center at Quantico, Virginia, as well as other FBI offices in Dallas and New Orleans.

"We've been working long hours since Saturday evening," Ogletree said Monday.

By 9:15 a.m. Monday, FBI agents had set up a blue tent on the front lawn, as hazardous materials experts and agents with the Bureau of Alcohol, Tobacco, Firearms and Explosives searched the property.

"There's a significant amount of material," said Larry Satterwhite, an assistant Houston police chief who oversees the Homeland Security Command. "Some very hazardous materials were found."

Satterwhite didn't say what type of explosives investigators found.

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Federal agents first raided the Schneck home in the 2000 block of Albans Road in 2013, when another multi-agency team stormed the property owned by his parents, Houston arts consultant Cecily E. Horton and her husband, Andrew Edward Schneck.

Agents also searched other properties in 2013 owned by the couple, including a Memorial-area home and a condo in Bryan.

Officials initially said the younger Schneck was believed to have chemicals that could be used to make nerve gas or tear gas. They eventually found a military-grade explosive called picric acid at the Memorial area home on Fall River.

The following year, the then 22-year-old Schneck pleaded guilty in federal court to knowingly storing explosives and was sentenced to five years probation. A judge released him last year ahead of schedule.

At the time, his lawyers noted his "'exemplary character," saying he'd "matured and his focus is no longer concentrated on high-risk activities," court documents show.

While on probation, he completed a bachelor's degree at Austin College, where he majored in chemistry. He expressed interest in attending graduate school to study chemical reactions using "cutting-edge computer learning software," according to court documents.

He adhered to the probation stipulations and paid off more than $150,000 in restitution.

"Schneck is not a risk to public safety nor is there a history of violence," his lawyers argued.

Photo: Steve Gonzales, Houston Chronicle

School acquaintances described him as an awkward loner who struggled with social interactions.

"I can't even think of a single friend he had, to be perfectly honest," said one former classmate at Memorial High School, where he was known as "Ace" for his initials.

During their senior year of high school, the former classmate said, Schneck wrote a "manifesto" dedicated to some of the school's popular girls, decrying how their boyfriends treated them and saying he could have done better.

After high school graduation in 2010, the two lost touch and Schneck's classmate didn't hear news of him again until charges were filed against him several years ago.

"None of this is surprising," the former classmate said. "He seems a bit disconnected from reality."

Dowling's statue — the city's first publicly financed monument — has prompted discussion for years.

A 1958 Houston Chronicle article acknowledged that "there probably are only a few Houstonians who have more than a hazy idea about Dick Dowling's contribution to Texas history."

"Shouldn't the city of his adoption revere the memory of such a daring young man and his exploits sufficiently to display the statue and keep it in good repair?" a front-page piece asked.

Dowling, a Houston businessman, is credited with helping found the Houston Fire Department and start the city's first street car company.

In recent weeks, protesters of Confederate statues tore down one such monument in Durham, North Carolina. Elsewhere, authorities in Baltimore and on the University of Texas at Austin campus removed public statues quietly in the night.

Critics here have also called for the removal of such statues but condemned Schneck's actions.

"If someone wants to take the initiative and take it down and face the consequences, I'm good with that," said Ashton Woods, an organizer with Black Lives Matter Houston. "But it becomes another thing if you have explosives enough to blow up your neighborhood and take them to a public park. I completely condemn that. You don't put people in danger to further your ideology."

Margaret Kadifa, John D. Harden, Lindsay Ellis and James Pinkerton contributed to this story.