Stinger, a member of Constitutional Patriots New Mexico Border Ops Team militia is pictured on patrol at the US-Mexico border near Mt. Christo Rey in Sunland Park, New Mexico on March 20, 2019. - The militia members say they will patrol the US-Mexico border near Mt. Christo Rey, "Until the wall is built." In recent months, thousands of Central Americans have arrived in Mexico in several caravans in the hope of finding a better life in the United States. US President Donald Trump has branded such migrants a threat to national security, demanding billions of dollars from Congress to build a wall on the southern US border. (Photo by Paul Ratje / AFP)        (Photo credit should read PAUL RATJE/AFP/Getty Images)
PHOTO: PAUL RATJE/AFP/Getty Images
Stinger, a member of Constitutional Patriots New Mexico Border Ops Team militia is pictured on patrol at the US-Mexico border near Mt. Christo Rey in Sunland Park, New Mexico on March 20, 2019. - The militia members say they will patrol the US-Mexico border near Mt. Christo Rey, "Until the wall is built." In recent months, thousands of Central Americans have arrived in Mexico in several caravans in the hope of finding a better life in the United States. US President Donald Trump has branded such migrants a threat to national security, demanding billions of dollars from Congress to build a wall on the southern US border. (Photo by Paul Ratje / AFP) (Photo credit should read PAUL RATJE/AFP/Getty Images)
Now playing
02:31
Armed militia group detains migrants at the border
Now playing
01:21
Lawmaker fires back at Tucker Carlson's QAnon spin
Sen. Lisa Murkowski (R-AK) asks a question at a hearing of the Senate Health, Education, Labor and Pensions Committee on September 23, 2020 in Washington, DC.
PHOTO: Alex Edelman/Pool/Getty Images
Sen. Lisa Murkowski (R-AK) asks a question at a hearing of the Senate Health, Education, Labor and Pensions Committee on September 23, 2020 in Washington, DC.
Now playing
01:40
Trump plans to campaign against Sen. Murkowski in 2022
Biden 03062021
PHOTO: CNN
Biden 03062021
Now playing
02:28
'Help is on the way': Biden speaks after Senate passes relief plan
Now playing
03:04
Schumer: Nobody said it would be easy, but it is done
01 senate stimulus bill 210306
PHOTO: Senate TV
01 senate stimulus bill 210306
Now playing
01:47
Senate passes Biden's $1.9 trillion Covid-19 relief bill
WASHINGTON, DC - MARCH 05: Sen. John Cornyn (R) (R-TX) talks with Sen. Joe Manchin (D-WV) while walking to the U.S. Senate chamber for a vote March 05, 2021 in Washington, DC. The Senate continues to debate the latest COVID-19 relief bill.  (Photo by Win McNamee/Getty Images)
PHOTO: Win McNamee/Getty Images
WASHINGTON, DC - MARCH 05: Sen. John Cornyn (R) (R-TX) talks with Sen. Joe Manchin (D-WV) while walking to the U.S. Senate chamber for a vote March 05, 2021 in Washington, DC. The Senate continues to debate the latest COVID-19 relief bill. (Photo by Win McNamee/Getty Images)
Now playing
02:54
Axelrod breaks down Manchin's surprising move
sinema
PHOTO: CNN
sinema
Now playing
01:50
Senator's move has many on the internet outraged
PHOTO: FBI
Now playing
02:58
Trump State Department official charged in Capitol riot
WASHINGTON, DC - JANUARY 06: U.S. Sen. Paul Gosar (R-AZ) speaks on the floor of the House Chamber during a joint session of congress on January 06, 2021 in Washington, DC. Congress held a joint session today to ratify President-elect Joe Biden's 306-232 Electoral College win over President Donald Trump. A group of Republican senators said they would reject the Electoral College votes of several states unless Congress appointed a commission to audit the election results. (Photo by Drew Angerer/Getty Images)
PHOTO: Drew Angerer/Getty Images
WASHINGTON, DC - JANUARY 06: U.S. Sen. Paul Gosar (R-AZ) speaks on the floor of the House Chamber during a joint session of congress on January 06, 2021 in Washington, DC. Congress held a joint session today to ratify President-elect Joe Biden's 306-232 Electoral College win over President Donald Trump. A group of Republican senators said they would reject the Electoral College votes of several states unless Congress appointed a commission to audit the election results. (Photo by Drew Angerer/Getty Images)
Now playing
02:19
This is what Rep. Gosar was posting days before Capitol riot
John King Magic Wall 0305
PHOTO: CNN
John King Magic Wall 0305
Now playing
02:17
President Biden sending a team to the US-Mexico border
Senior Advisor to the President Jared Kushner  attends a press conference on September 4, 2020, in the Brady Briefing Room of the White House in Washington, DC. (Photo by Brendan Smialowski / AFP) (Photo by BRENDAN SMIALOWSKI/AFP via Getty Images)
PHOTO: BRENDAN SMIALOWSKI/AFP/AFP via Getty Images
Senior Advisor to the President Jared Kushner attends a press conference on September 4, 2020, in the Brady Briefing Room of the White House in Washington, DC. (Photo by Brendan Smialowski / AFP) (Photo by BRENDAN SMIALOWSKI/AFP via Getty Images)
Now playing
02:50
Jared Kushner disappears from Trump's inner circle
Rep john garamendi 0305
PHOTO: CNN
Rep john garamendi 0305
Now playing
02:33
Rep. Garamendi: Any lawmaker involved in Capitol riots ought to be thrown out of Congress
Protesters gather at Lincoln Park to demand the Emancipation Memorial be taken down on June 23, 2020 in Washington, DC.
PHOTO: Tasos Katopodis/Getty Images
Protesters gather at Lincoln Park to demand the Emancipation Memorial be taken down on June 23, 2020 in Washington, DC.
Now playing
03:01
Why some people want this Abraham Lincoln statue taken down
psaki
PHOTO: CNN
psaki
Now playing
00:56
Psaki fires back at Trump testing czar over vaccine claims
PHOTO: CNN
Now playing
03:04
Avlon: Pence's op-ed is 'way worse than Stockholm syndrome'
(CNN) —  

They’d been keeping watch near the border for weeks, drawing little notice as they shared live videos from their desert outpost.

But after posting videos last week showing armed men wearing military fatigues detaining migrants who just crossed the border into New Mexico, a militia group known as the United Constitutional Patriots now finds itself under fire.

State authorities in New Mexico have condemned the group. The American Civil Liberties Union accuses the militia of kidnapping migrants. And now a leader of the group is facing charges of illegal weapons and ammunition possession brought by the FBI.

Members of the United Constitutional Patriots haven’t responded to CNN’s requests for comment. But here’s what we know so far about the group, based on what authorities are saying, social media posts and local media reports:

The group has a growing Facebook following, but a small number of members camping near the border

Court documents unsealed Monday provide new details about United Constitutional Patriots and its leadership.

Reports to an FBI tip line alleged “militia extremist activity in Flora Vista, New Mexico” and identified Larry Mitchell Hopkins as the so-called commander of United Constitutional Patriots, an FBI special agent’s affidavit says.

Those October 2017 reports, the affidavit says, led authorities to search Hopkins’ home the next month.

“Information also was conveyed that the group had its ‘base’ at Hopkins’s residence, was supported by approximately 20 members, and was armed with AK-47 rifles and other firearms,” the affidavit says.

In more recent descriptions of the group, its ranks at the border have been smaller than the 20 members mentioned in court documents.

Two months ago, a social media post from a spokesman for the group reported there were about a dozen militia members camped out near the border. More recently, other media reports have offered a smaller figure. Earlier this month, the Agence France-Press news agency reported there were about half a dozen militia members at the United Constitutional Patriots’ camp in Sunland Park, New Mexico.

They’ve said they’re staying put until President Trump’s border wall is built

The New York Times reported that Jim Benvie, a spokesman for the group, said the organization “plans to remain on the border until the extended wall proposed by President Trump is built or Congress changes immigration laws to make it harder for migrants to request asylum.”

“We’re just here to support the Border Patrol and show the public the reality of the border,” Benvie said, according to the Times.

They drew widespread attention last week after posting videos of migrants detained at gunpoint

Videos shared on the United Constitutional Patriots New Mexico Border Ops Facebook page purport to show members of the group detaining migrants, including families with children, who have just crossed the border.

They show people often in full military fatigues, with handguns strapped to their sides, wearing gloves and black masks. Armed men order migrants to stop, force them to sit on the ground and then apparently call Border Patrol to pick them up. At least two videos posted on the group’s Facebook page depict a man in fatigues verbally identifying himself as “Border Patrol” as he stops a group of migrants.

New Mexico’s attorney general told CNN that an armed group had detained nearly 300 people near the border.

“These individuals should not attempt to exercise authority reserved for law enforcement,” he said.

The ACLU accused them of kidnapping. A group spokesman said they were making ‘citizen’s arrests’

“We cannot allow racist and armed vigilantes to kidnap and detain people seeking asylum,” the ACLU of New Mexico said in a letter to state authorities last week. “We urge you to immediately investigate this atrocious and unlawful conduct.”

The New York Times reported that Benvie, the militia group’s spokesman, said their actions were legal, “comparing the detention of the migrants to ‘a verbal citizen’s arrest.’”

New Mexico’s governor said state and local authorities were looking into the matter.

“Menacing or threatening migrant families and asylum-seekers is absolutely unacceptable and must cease,” Gov. Michelle Lujan Grisham said on Twitter.

Then the group’s leader got arrested over the weekend

Hopkins, 69, was arrested Saturday on charges stemming from a November 2017 search FBI agents conducted at his residence.

During the search, according to an affidavit, the agents found nine firearms and ammunition. Because Hopkins had previously been convicted of several felonies, including impersonating an officer in Oregon in 2006, he was prohibited from possessing firearms or ammunition, according to the complaint.

Court documents don’t explain why authorities waited to arrest Hopkins until Saturday, more than a year after they searched his residence.

He’s charged with being a felon in possession of a firearm and ammunition. If he’s convicted, he could face up to 10 years in prison.

His attorney could not be immediately reached for comment. Authorities have said he’ll remain in custody while he awaits a preliminary hearing set for 11:30 a.m. on April 29.

The group’s fundraising efforts hit a snag last week

As word spread about the group’s activities, several websites used for crowdfunding banned United Constitutional Patriots from their platforms.

In a Facebook post over the weekend, the group said PayPal and GoFundMe “will not provide their donation services to us anymore.”

GoFundMe spokeswoman Katherine Cichy said in a statement that a campaign from the group had been removed “because it violated GoFundMe terms and conditions.”

A Paypal spokesman said the company has canceled United Constitutional Patriots’ account.

“The organization was found to have violated our user agreement and the account was canceled last week,” spokesman Justin Higgs said in an email.

CNN’s Artemis Moshtaghian and Casey Hicks contributed to this report.