These are the symbols pedophiles use to signal their sordid sexual preferences.

The seemingly innocuous pastel-colored scrawls feature butterflies, love hearts, and spirals.

But to FBI agents they signify something much darker.

One of the symbols, a blue spiraling triangle framed by another triangle, is known as the BoyLover logo. It is used by pedophiles who prefer young boys.

Another is for pedophiles who prefer much younger boys. This symbol, known as the LittleBoyLover logo, is also a blue triangle spiral, but drawn in a child-like scrawl.

The so-called GirlLover logo is a heart inside a heart, indicated that the male or female pedophile prefers young girls.

Pedophiles who do not have a preference of gender use the ChildLover logo, which is a butterfly made up of love hearts.

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Boys: The FBI found five symbols pedophiles use to indicate their preferences. This symbol, a blue spiraling triangle framed by another triangle, is known as the BoyLover logo, used by adults who prefer young boys

Younger boys: This symbol is for pedophiles who prefer much younger boys. Known as the LittleBoyLover logo, it is also a blue triangle spiral like the BoyLover logo, but it is drawn in a child-like scraw

Girls: The so-called GirlLover logo is a heart inside a heart, indicated that the pedophile prefers young girls

Finally, there is the Childlove Online Media Activism logo, which pedophiles use as a symbol to promote their 'cause': that sexual relationships between adults and minors should be decriminalized.

The symbol - a triangle, a love heart and a circle merged into one - has been circulating social media, blogs and webcasts for years. It has even appeared on some children's toys.

Investigators with the FBI's Cyber Division Innocent Images National Initiative first discovered the code in 2007.

Compiling them into a PDF document, the agents sent them to law enforcement agencies around the country.

The document has since emerged publicly after it was published on WikiLeaks.

It includes pictures of the symbols etched into rings, formed into pendants, and imprinted on coins.

'Pedophilia symbols on jewelry, coins, Web sites and other effects are indicative of advertisement methods used by child sexual predators to promote their cause,' the document reads.

'Pedophile activists advocate for the social acceptance of sexual relationships between adults and children.

'These organizations seek to decriminalize sexual relationships between adults and children and to legalize child pornography based on their belief that children have the ability to consent to sexual acts.

Any gender: Pedophiles who do not have a preference of gender use the ChildLover logo, which is a butterfly

Pedophile promotion symbol: This is the Childlove Online Media Activism logo, which pedophiles use as a symbol to promote their 'cause': that sexual relationships between adults and minors should be decriminalized

'Identical or similar jewelry and symbols as described in this intelligence bulletin should raise suspicion of possible pedophilia activity when found during searches.'

The comprehensive account of the code has emerged a month after Monster Jam was forced to recall a line of toy trucks which featured symbols bearing a horrifying similarity.

Nicole O'Kelly, a mother in Syracuse, New York, bought the pink-and-black toy for her two-year-old daughter.

But her older daughter recognized the symbols, which appeared in an episode of Law & Order: Special Victims Unit, which tackled pedophilia.

Anna Potter, associate executive director of the Bivona Child Advocacy Center in Rochester, New York, told WHEC News: 'When I see that heart inside the heart, it’s pedophile. It’s that underground culture that they use to communicate.'

Feld Entertainment, which built the toy, recalled the item and issued a statement, insisting the firm was unaware of the meaning behind the symbols.