Three people, including an aide to state Atty. Gen. Kamala D. Harris, have been arrested, accused of operating a rogue police force claiming to exist for more than 3,000 years. The so-called Masonic Fraternal Police Department claims to trace its origins to the Knights Templar, which it called the “first police department.” Here’s a quick way to catch up on your facts about the ancient, secretive order and the organizations it has inspired:

The original Knights Templar was founded in the 12th century to protect Catholic pilgrims during the Crusades.

Contrary to what’s claimed on a website appearing to belong to the MFPD, the Knights Templar were not founded in 1100 B.C., says Jennifer Paxton, a professor of medieval history at the Catholic University of America in Washington, D.C.

The Knights Templar order was formed in 1119 A.D. during the First Crusade to protect Jerusalem, but the order wasn't a police department.

The knights were recruited to provide safe passage for Catholic pilgrims traveling through the Holy Land to Jerusalem, which had just been recaptured by the Christians. Some historians have suspected they were actually tasked with retrieving precious relics during the wars.

The order was founded in Jerusalem -- some say at the Church of the Holy Sepulchre, the spot marking Jesus’ crucifixion. The order's headquarters was on the Temple Mount (Mount Zion), which only added to the knights' intrigue and associations with early Christian history.

The Knights Templar existed for about 200 years, and answered only to the pope.

Bernard of Clairvaux, the most powerful European monk at the time, spearheaded the campaign to recruit these warrior-monks after helping founding grandmaster Hugues de Payens establish the order.

About 10 years after the order was founded, the pope named it an official and permanent military religious order within the church, giving its members unprecedented powers, Paxton says.

They answered only to the Pope: kings and local bishops had no control over them.

The knights took vows of poverty and chastity, and were trained killers. They did have secret rituals, Paxton says, but “probably no more nefarious than your average fraternity initiations.”

While its members remained poor as individuals, the order amassed great wealth through church tithes and donations of land and estates from devout Catholics. With their network of treasuries and ability to move money between the east and west, the Templars soon became bankers for pilgrims and rulers alike, financing regional wars and holding valuable real estate, Paxton says.

At the height of the order, tens of thousands of knights, employees and caretakers were believed to be associated with it, according to Paxton.

The king of France ordered the Knights Templar rounded up, arrested and burned at the stake.

King Philip IV of France coveted the Templars’ fortune so he could finance his own wars, some historians say. Others believe Philip owed the order a large sum of money, Paxton says.

The king is said to have pressured Pope Clement V to dissolve the Templars and order the mass arrest of all Templar knights in France on Oct. 13, 1307. They were charged with heresy and committing immoral sexual acts.

Many Templars were tortured into giving false confessions. Dozens were burned at the stake, including the order’s last grandmaster, Jacques de Molay.

In 2007, the Vatican revealed parchments from the Vatican Secret Archives, which showed that Pope Clement had originally cleared the Templars of the heresy charges. The immorality charges had apparently stood.

Bowing to pressure from King Philip, Clement suppressed his findings and abolished the order.

The legend of the Knights Templar has inspired plenty of fiction, and claims from modern-day groups that trace their origins back to the Templars.

The mystery and secrecy that have shrouded the Templars have contributed to far-fetched stories over the centuries.

Among those is the legend of the Holy Grail (yes, the same Holy Grail that Monty Python’s motley crew sought). When the story of the Holy Grail, the chalice used by Christ at the Last Supper, began to circulate, it was almost immediately linked to the Templars, mostly because of their prominence in the Crusades and their association with many sacred, historical aspects of Christianity, according to author Michael Haag, who wrote "The Templars: The History and the Myth" and spoke to The Times in 2010.

Publication of Dan Brown’s novel "The Da Vinci Code" renewed interest in the secretive order, with a storyline that claimed the Templars were founded to guard the secret of the Holy Grail – which, in the book, is Mary Magdalene herself, portrayed as the wife of Jesus and mother of his child.

The Freemasons, an organization that’s regarded as one of the oldest continuous secret societies, is often confused with the Knights Templar. But, Paxton says, that order was established hundreds of years after the Templars were dissolved, and while Freemasons may have drawn much of their inspiration from Templar lore, they were not directly tied to the knights’ order.

There also are several modern-day organizations that draw their name from the Templars, or claim some connection to the order.

The Order of the Temple of Solomon claims on its website that it is a “full and official restoration” of the Templar line, re-established in 2013.

The Masonic Fraternal Police Department’s mission statement claims the department “is the Knights Templar’s,” according to a website that claims to represent the group.

Paxton’s take? “Baloney.”

In fact, she says, there is no evidence that suggests a connection between the Templars who were abolished in the 14th century and any current organization.

“It’s fine if people want to take the Templars as an inspiration,” Paxton says, “but what you can’t do is claim a continuity that doesn’t exist.”

Among the conspiracy theories some right-wing groups ascribe to is that descendants of the Knights Templar (and other organizations such as the Freemasons) are behind organizations such as the World Bank, the International Monetary Fund, NATO, the European Union, the United Nations and even the Skull and Bones Society at Yale, according to Mark Potok, a senior fellow at the Southern Poverty Law Center.

According to Potok, extremist groups such as the Ku Klux Klan were experiencing a resurgence in the 1920s, just as fascination with – and membership in – secret societies was peaking in the United States. “It was a fad. All these groups had various rites and names,” Potok says. “[The KKK] were absolutely inspired by older secret societies.” This might explain their use of such titles as Imperial Wizard and Grand Cyclops, but, he reiterates, there's no credible connection between those groups and the Freemasons or Templars.

Paxton says the drama of the Templars’ rise and fall may explain why they have fascinated people for centuries.

“They were so dominant and so powerful and they were just cut down almost at one blow,” Paxton says. “That is a startling reversal of fortune, and I think one of the things people are captivated by. They think such a powerful organization cannot utterly have disappeared; it had to have gone underground and continued.”