A member of the US Secret Service looks out from the roof of the White House in Washington, DC on August 21, 2021.A member of the US Secret Service looks out from the roof of the White House in Washington, DC on August 21, 2021.

Two sources told NBC News that the internal watchdog of the Department of Homeland Security is investigating the destruction of Secret Service phone text messages.

The Inspector General of the Department of Homeland Security ordered the Secret Service to stop any internal investigations into the deleted text messages.

The House select committee investigating the Capitol riot issued a subpoena to the Secret Service seeking text messages after learning that messages from January 5 and 6, 2021, had been erased.

The committee said the Secret Service may have broken federal records-keeping law.

The Secret Service must not engage in any further investigative activities to ensure the integrity of the investigation, according to a letter written by the deputy inspector general of the Department of Homeland Security.

It includes immediately refraining from interviewing potential witnesses, collecting devices or taking any other actions that would interfere with an ongoing criminal investigation.

The Secret Service received a letter from the Department of Homeland Security.

The Inspector General requested that the Secret Service conduct a legal review to make sure that they do not conflict with each other.

Hours before the House select committee was set to hold a hearing into President Donald Trump's actions, news of the criminal probe came.