HENRICO, Va. (WTVR) -- Residents in one West End community wanted to know what federal agents and undercover police officers were doing in their neighborhood Thursday afternoon.

CBS 6 reporter Jon Burkett found out it has something to do with an investigation involving sex crimes against animals.

Travis Vice was cleaning his car that afternoon when he witnessed a number of unmarked cruisers swarming a townhouse parking lot off Ashinghurst Road in Henrico's far West End.

"There were undercover officers, FBI, apparently looking for somebody,” Vice said. “I'm concerned about what's going on around me and looks like I need to get to know my neighbors better."

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According to a search warrant affidavit obtained by CBS 6 and online court documents, the man living in this home was arrested and charged with five counts of production, publication, sale, and possession of obscene items.

Investigators say the alleged obscene material involves male dogs.

The affidavit contains graphic details, but here is what we can tell you: it states that computers, cameras and other electronics were removed from the townhouse. It also spells out how a member of the Fairfax County Police Child Exploitation Unit first encountered the Henrico man on the website Craigslist.

Investigators allege the accused posted a message in the 'personals-casual encounters' section entitled "taboo, fantasies of the knot."

The detective who has more than 13 years of experience, has conducted several investigations involving Craigslist, and alleges the term 'the knot' relates to the practice of bestiality, or sex involving a person and an animal.

The affidavit also states the Henrico man emailed the undercover agent videos of dogs engaged in sex acts with people.

"If he is found guilty of something, then I think a judge will certainly weigh the danger to the public aspect, even if it only involves animals," said CBS 6 legal expert Todd Stone.

Fairfax Police are the lead investigators in this case, though neighbors say they also saw Henrico officers on the scene during the raid.

Sources say that federal agents are involved in the case because of their expertise in retrieving media files from computer hard drives.