A half-dozen nonprofit groups opposed to concentrated corporate power are seeking a congressional investigation into tech company employees encrypting or deleting internal messages to destroy evidence in antitrust cases. 

“We are disturbed by recent reports that the tech giants have yet again been caught systematically deleting internal messages and chats tied to active federal investigations, thus concealing them from regulators and the courts,” the groups wrote in a letter to the top lawmakers on the Senate and House Judiciary committees dated Monday. They cite findings from a judge and accusations by the Federal Trade Commission that these practices are taking place.

“This behavior is not new, but it has grown steeply in recent years,” the groups wrote, calling on lawmakers to investigate the alleged practice “to safeguard the power of the federal government to enforce antitrust laws and regulations in good faith.” 

The letter from The Tech Oversight Project, American Economic Liberties Project, Demand Progress, Institute for Local Self-Reliance, NextGen Competition and the Revolving Door Project was provided to CQ Roll Call. The letter pointed to several instances in which tech companies including Google LLC, Amazon.com Inc. and Apple Inc. likely destroyed evidence that could have implicated them in legal proceedings. 

Judge Amit P. Mehta of the U.S. District Court for the District of Columbia, who’s overseeing the Justice Department’s antitrust case against Google, told the company that it was “negligent” for not retaining records and for implementing a policy of automatically destroying employees’ internal messages after 24 hours. 

“Google’s document retention policy leaves a lot to be desired,” Mehta said at a May 3 hearing, according to The Associated Press. “It’s shocking to me that a company would leave it to its employees to decide when to preserve documents.”

A Google lawyer defended the policy and told the court that it was a “reasonable” practice, the AP said. Justice Department lawyers have asked the court to sanction Google for destroying documents.  

The Justice Department antitrust case against Google, one of the largest in recent history, argues that the company’s market dominance in online advertising allows it to jack up prices. Google has said it has plenty of online competition.

In another instance in which a company’s executives stand accused of destroying evidence, the Federal Trade Commission in March accused Amazon executives of using the Signal app to hide evidence. 

“Amazon executives systematically and intentionally deleted internal communications using the ‘disappearing message’ feature of the Signal messaging app,” the FTC said in a court filing. 

Amazon has said the FTC’s allegations are “baseless.” 

The letter is addressed to Senate Judiciary Chair Richard J. Durbin, D-Ill.; the committee’s ranking member, South Carolina Republican Sen. Lindsey Graham; House Judiciary Chairman Jim Jordan, R-Ohio; and ranking member Jerrold Nadler, D-N.Y., as well as the top lawmakers on two subcommittees.