A watchdog agency learned in February that the Secret Service had purged nearly all cellphone texts from around the time of the Jan. 6, 2021, attack on the Capitol, but chose not to alert Congress, according to three people briefed on the internal discussions.

That watchdog agency, the Department of Homeland Security’s Office of Inspector General, also prepared in October 2021 to issue a public alert that the Secret Service and other department divisions were stonewalling it on requests for records and texts surrounding the attack on the Capitol, but did not do so, the people briefed on the matter said. They spoke on the condition of anonymity to discuss sensitive internal investigations.

The previously unreported revelation about the inspector general’s months-long delay in flagging the now-vanished Secret Service texts came from two whistleblowers who have worked with Inspector General Joseph V. Cuffari, the people knowledgeable about the internal discussions said.