There's a good whodunit developing over at The Pirate Bay, the popular BitTorrent file-sharing service.

An unknown entity has launched a large distributed denial-of-service attack (DDoS) against The Pirate Bay and rendered the site largely inaccessible for more than a day. The Pirate Bay posted a note to its Facebook page confirming the attack. Site operators wrote: "We don't know who's behind it but we have our suspicions."

Suspicions are all anybody seems to have at this point. Here's a list of the top suspects and where they stand on the issue.

The Motion Picture Association of America: A spokesman for the trade group for the top six Hollywood film studios, a group that over the years has become one of The Pirate Bay's arch nemesis, told CNET "The MPAA has no involvement and does not condone DDoS attacks."

A spokesman for the trade group for the top six Hollywood film studios, a group that over the years has become one of The Pirate Bay's arch nemesis, told CNET "The MPAA has no involvement and does not condone DDoS attacks." The Recording Industry Association of America: A representative for the trade group for the four major music labels, also denied that the organization was behind the attack. He pointed out that the RIAA has been the victim of multiple DDoS attacks and has denounced the practice.

A representative for the trade group for the four major music labels, also denied that the organization was behind the attack. He pointed out that the RIAA has been the victim of multiple DDoS attacks and has denounced the practice. Anonymous: The mysterious hacktivist group that is well known around the world for launching DDoS attacks, has denied responsibility. The Pirate Bay admonished Anonymous' for its tactics when the group recently launched a DDoS attack against Virgin Media, the first Internet service provider in the United Kingdom to block The Pirate Bay. "Yes, The Pirate Bay is down," wrote Anonymous in a Twitter post. "Yes it's under DDoS attack. No we don't know who from. We'll update as we hear more."

Of course the MPAA and RIAA don't speak for every copyright owner around the world. Plenty of filmmakers and musicians not affiliated with those groups consider The Pirate Bay a scourge and believe that site operators enrich themselves at artists' expense.

Anonymous also doesn't speak for every hacker in the world or for everyone who has the capability to launch a DDoS attack.

The only reason that anyone would even suspect Anonymous, which has always been a huge supporter of The Pirate Bay, is because of BitTorrent site's strong condemnation last week of DDoS attacks -- even attacks launched in support of the service.

"We do not encourage these actions," The Pirate Bay wrote after Virgin Media came under attack, according to the blog Torrentfreak. "We believe in the open and free Internets, where anyone can express their views. Even if we strongly disagree with them and even if they hate us."

So, where does this leave us? Is it a government that is attacking the site or an angry group of tech-savvy indie filmmakers or musicians? Is it a rogue element of Anonymous? If you have any suspicions, please share them in the comments.