Outfitted in dark suits and black sunglasses, Secret Service agents try to blend in.
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Occasionally, though, they make headlines, as some members did over the weekend after they were relieved of duty amid allegations of involvement with prostitution. That prompts the question: What exactly does the Secret Service do?
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Founded in 1865 as part of the Treasury Department, the Secret Service to this day is charged with investigations involving counterfeiting in addition to protecting top federal officials, visiting foreign dignitaries, and major political candidates.
Here's a look at the agents on the job:
A Secret Service detail looks out from atop the Pentagon during a ceremony marking the 10th anniversary of 9/11.(AP Photo/J. Scott Applewhite)
A Secret Service agent stands watch outside as then-Republican presidential candidate Rick Santorum (background) talks to reporters in Louisiana.(AP Photo/Gerald Herbert)
Secret Service Special Agent Jeff Eisenbeiser shows how to look for a watermark while holding up a counterfeit $50 bill during a news conference in 2005.(AP Photo/Keith Srakocic)
Secret Service Special Agent Jason Swierkowski holds a plastic bag with counterfeit $100 and $20 notes recovered during a 2008 investigation.(AP Photo/Damian Dovarganes)
A Secret Service agent closes the door to President Obama's limousine after arriving at the Orlando International Airport in Florida earlier this year.(AP Photo/Phelan M. Ebenhack)
A member of the Secret Service looks on as Herman Cain delivers a speech in Atlanta in December announcing the suspension of his campaign for the Republican presidential nomination. (AP Photo/David Goldman)(AP Photo/David Goldman)
Secret Service agents surround Republican presidential candidate Mitt Romney as he signs autographs at a campaign rally.(AP Photo/Gerald Herbert)
A Secret Service agent stands watch as Rick Santorum campaigns in Brookfield, Wis., in March.(AP Photo/Jae C. Hong)