Dec 21 (Reuters) - Chicago Police arrested 50 people for using "secret groups" on Facebook to sell guns and drugs, the police said on Thursday, and they criticized the world's biggest social media network as being unhelpful during the 10-month investigation.
Police did not detail the charges filed against the 50 men and women arrested through Thursday, but said there were "dozens and dozens" of the secret groups. Arrest warrants for 18 more have been signed and most of those affected have criminal histories, police said.
Chicago Police Superintendent Eddie Johnson, at a news conference to announce the arrests, criticized Facebook for not helping police.
"Facebook has a responsibility to the people that they serve to ensure that these types of things don't go on," Johnson said. "And, quite frankly, they haven't been very friendly to law enforcement to prevent these things."
Johnson expressed hope that public attention to the issue will pressure Facebook to work to quell criminal activity by some of its 2 billion users worldwide.
"Certainly they can spend a little money to ensure that these type of things don't happen," Johnson said.
Facebook Inc did not immediately respond to phone calls or emails seeking comment.
Johnson and Anthony Riccio, chief of the organized crime unit, did not make clear how much Facebook knew of the investigation. Riccio declined to say whether police have been in contact with the company, saying that was "ongoing."
Among those arrested was an elementary school teacher taken into custody at his Chicago school in possession of scales often used for weighing drugs, Riccio said.
Since a confidential informant alerted investigators about the alleged criminal trade on Facebook in February, police arranged the purchase of 17 different types of drugs and 18 different illegal firearms, Riccio said.
Chicago has been singled out by President Donald Trump as one of the most violent U.S. cities, where in 2016 murders exceeded 760.
Riccio said investigators created covert identities on Facebook and were invited into secret groups, which are closed unless the user-administrator allows someone to join. Police then monitored messages and contacted those in the group via Facebook to make buys. (Reporting by Bernie Woodall in Fort Lauderdale, Fla.; Editing by Leslie Adler)