A Secret Service agent assigned to Barack Obama was breaching security while leading a double life, according to a memoir by the agent's former girlfriend.

Janet Napolitano was secretary of Homeland Security from 2009-2013 and currently serves on the president’s Intelligence Advisory Board.

A former senior official with the Secret Service, Donald Mihalek, discusses the new report that reveals systemic issues within the agency.

"Without reform" to the Secret Service "another Butler can and will happen again," DHS independent review finds

A special commission launched by the Homeland Security secretary concludes that the assassination attempt on former President Trump points to more risks within the agency's protection.

Secret Service develops guide for state and local law enforcement to prevent "targeted violence"

ABC News’ Jay O’Brien reports on the hearing led by a committee investigating the assassination attempt on former President Donald Trump in Butler, Pennsylvania.

A Secret Service agent is under investigation for an alleged sexual misconduct incident with an aide of Vice President Kamala Harris, the campaign said.

Glenn Ivey, D-Md., a member of the House Committee on Homeland Security and the task force on the attempted assassination of former President Trump, joins to speak about the investigation.

George Stephanopoulos interviews Rep. Mike Kelly, R-Pa., and Rep. Jason Crow, D-Colo., members of the Trump assassination attempt task force, on “This Week.”

The report released by the U.S. Secret Service details problems with communication and drone capabilities ahead of July's attempted assassination of former President Donald Trump.

The 405-0 House vote follows a second Trump assassination attempt.

Issues with a host of communications and technical difficulties with drone capabilities plagued the U.S. Secret Service at the rally in Butler, Pennsylvania

The Secret Service failed to secure the line of sight to the former president by not securing the roof of the AGR building near the Butler Fair Grounds, according to a new report.

The acting Secret Service director encouraged former President Trump to give as much notice as possible before his golf outings, a source told ABC News.

Trump’s golf course protection worked as intended amid a second assassination attempt.

Former President Donald Trump praised the Secret Service's actions in stopping an alleged assassination attempt Sunday during a phone conversation with ABC News Tuesday

Steve Witkoff -- a friend of former President Donald Trump -- told "Good Morning America" Secret Service were "exemplary" during Sunday's apparent assassination attempt.

President Biden said the Secret Service "needs more help" as he briefly addressed the apparent assassination attempt against Donald Trump.

President Joe Biden called on Congress to review whether the agency needs more personnel in the wake of a reported second assassination attempt on former President Donald Trump.

Sources say multiple secret service agents have been put on administrative duties following Trump’s assassination attempt.

A gunman attempted to kill former President Trump at a rally on July 13.

Sources tell ABC News that at least five Secret Service agents who were involved in planning the rally in Butler, Pennsylvania, have been reassigned, after the attempted assassination of Donald Trump.

Former President Donald Trump was shot in July at an outdoor rally in Butler, Pennsylvania.

The Secret Service is making arrangements for former President Trump to resume outdoor campaign rallies by surrounding his podium with bulletproof glass, sources say.

The acting head of the Secret Service blamed his agency for the attempted assassination of Donald Trump in Butler, Pennsylvania. Ronald Rowe called it "a Secret Service failure."

Acting Secret Service Director Ronald Rowe called the security gaps that led to the attempted assassination of former President Donald Trump a “complete failure."

Acting Secret Service Director Ronald Rowe and FBI Deputy Director Paul Abbate were grilled by lawmakers about the attempted assassination attempt against Donald Trump.

Text messages between local snipers show they noticed Thomas Matthew Crooks nearly two hours before the assassination attempt on former President Donald Trump.

FBI Director Christopher Wray revealed more details on the suspect leading up to and after the shooting, including use of a drone and explosives found in the suspect's car

Trump's attempted assassination has had a reverberating effect around the nation, felt most closely by the agency tasked with protecting him, the U.S. Secret Service.

Secret Service Director Kimberly Cheatle, who came under scrutiny for the agency’s failure to prevent the assassination attempt on Donald Trump, has resigned.

In the aftermath of a contentious hearing on Capitol Hill and bipartisan calls for her resignation, Kim Cheatle took responsibility for the attempted assassination of Donald Trump and stepped down.

Former Director Kimberly Cheatle testified before the House Oversight Committee, calling the attempt the “most significant operational failure of the secret service in decades.”

The congressional hearing with the now-former Secret Service director on Monday also sparked an intense public debate over gun violence.

Director Kimberly Cheatle announced her resignation in an email to Secret Service employees Tuesday morning.

On Monday, Cheatle told Congress that the attempted assassination against former President Donald Trump was the "most significant operational failure at the Secret Service in decades."

Secret Service Director Kim Cheatle appeared before Congress Monday, admitting that the shooting was the “most significant operational failure” since the attempt to assassinate President Ronald Regan.

Rep. Mike Turner, R-Ohio, questioned Kimberly Cheatle about the threat assessment of the Trump rally.

The Secret Service director took responsibility and called the assassination attempt against former President Donald Trump the biggest Secret Service operational failure in decades.

In her first hearing before Congress, Kim Cheatle also told the committee she will move "heaven and earth" to ensure that what occurred never happens again.

Facing bipartisan calls to resign, Secret Service Director Kim Cheatle testified on Capitol Hill, acknowledging the assassination attempt on Trump was a significant operational failure.

Kimberly Cheatle testified before the House Oversight Committee on Monday about the security failures that led to the assassination attempt against former President Donald Trump on July 13.

The U.S. Secret Service director told Congress on Monday that the agency failed in protecting former President Donald Trump at his rally on July 13.

In her first hearing before Congress, Secret Service Director Kim Cheatle said she takes "full responsibility for any security lapse."

Embattled Secret Service Director Kimberly Cheatle has no plans to resign after a group of GOP senators asked her to do so in a confrontation at the RNC.

Cheatle, the head of the Secret Service, previously served on then-Vice President Joe Biden's security detail.

In the wake of the assassination attempt on Donald Trump, Secret Service director Kimberly Cheatle, and the agency, have faced scrutiny for failing to prevent the attack.

ABC News spoke with an agent responsible for security in Chicago and Milwaukee.

A U.S. Secret Service agent was robbed at gunpoint in Tustin, California, over the weekend, according to police.