Homeland Security Secretary Janet Napolitano told lawmakers the investigation into the Secret Service prostitution scandal is still ongoing and that investigators would "leave no stone unturned."
She was called to testify before a Senate Judiciary Panel Wednesday about the ongoing investigation of the incident that marred President Obama's recent trip to Colombia.
While acknowledging that the agents' behavior was "inexcusable," she told Senate Judiciary Committee the Secret Service never put the president's security at risk.
Her testimony comes as Sen. Chuck Grassley, R-Iowa, is asking whether the Colombian prostitutes at the center of the Secret Service scandal could have actually been Russian spies.
"Who knows who might be using prostitutes? The Russians are famous for that to get information out of us," the Republican said during an interview with Radio Iowa. "You want to know that the president is protected."
Grassley is also questioning how the White House reached such a quick conclusion in its internal investigation of the incident.
He has called for an inspector general to assess any role the White House staff may have played in the case.
The Secret Service is trying to bring a fast resolution to the scandal. The agency said it has now settled the fate of all 12 agents involved.
Two more agents were ousted Tuesday, another was stripped of his security clearance, and one more was cleared of wrongdoing.
Six had already been forced out, and two others had previously been cleared of wrongdoing.
On the U.S. military side of the scandal, a 12th member of the Armed Forces has now been implicated. The Pentagon has suspended the security clearances of all the military personnel who are under review.