Prosecutors in St. Louis, Missouri, have seemingly allowed three robbery suspects to go free instead of explaining law enforcement’s use of a stingray in court proceedings.

The St. Louis case provides yet another real-world example where prosecutors have preferred to drop charges instead of fully disclose how the devices, also known as cell-site simulators, work in the real world. Last year, prosecutors in Baltimore did the same thing during a robbery trial.

According to the St. Louis Post-Dispatch, the dismissal this month came just one day before a St. Louis police officer was set to be deposed in the robbery case where three men and a woman were accused of stealing from seven people in September 2013.

Neither the office of Circuit Attorney Jennifer Joyce nor the office of Megan Beesley, a public defender involved in the case, immediately responded to Ars’ request for comment over the weekend. The St. Louis Police Department also did not respond to Ars’ request for comment.

UPDATE 6:22pm CT: Lauren Trager, the spokeswoman for the St. Louis Circuit Attorney’s Office, wrote to Ars: "Please note, despite the perspective of the defense attorney in this matter, the dismissal of the cases was not related in any way to any technology used in the investigation."

While the St. Louis newspaper did not name the suspects, it reported that an unnamed Circuit Attorney spokesman denied any connection between the dismissal and the forthcoming deposition.

According to court records provided by the Post-Dispatch, detective John Anderson told defense attorneys that the cops had used a "proven law enforcement technique" in order to locate one of the stolen phones and eventually the suspects. Anderson refused to elaborate, citing a non-disclosure agreement that he and his agency were bound by.

This revelation strongly suggests that the St. Louis Police Department has an agreement along the lines of one recently revealed in a court case in Erie County, New York. In that case, a rare unredacted form demonstrated the full extent of the FBI's attempt to quash public disclosure of stringray information. The most egregious example from the document showed that the FBI would prefer to drop a criminal case in order to protect secrecy surrounding the stingray.

Brandon Pavelich, one of the victims who was pistol-whipped and needed 18 stitches, told the Post-Dispatch that "he was ‘shocked’ when prosecutors told him the charges were dropped and explained only that ‘legal issues’ had developed."

The paper continued: