A 25-year veteran of the United States Secret Service, Merletti has also served as Assistant Director in the Office of Training, and as the Special Agent in Charge of the Presidential Protection Division.

[3] Federal and Government Courses During his time in the Secret Service, he completed Special Agent Criminal Investigator Training; Polygraph Examiner School; Counter Assault Team Training Course; Leadership Development Program and Followup (at the Center for Creative Leadership); Negotiating Skills for Executives; and George Washington Contemporary Executive Development.

He earned numerous military honors including the Bronze Star, Certificate of Achievement of Meritorious Performance, Combat Medical Badge, Good Conduct Medal, and Parachute Wings.

[5] His career transition from a highly decorated combat medic to his later roles is a testament to his character and exemplary on the job performance.

On April 29, 1993, The United States Department of the Treasury's Secretary Lloyd Benson and Assistant Secretary Of The Treasury for the Office of Enforcement, Ronald K. Noble, announced its plans to examine the Bureau of Alcohol Tobacco and Firearm's (ATF) execution of search and arrest warrants for David Koresh and other Branch Davidians at their compound near Waco, Texas on February 28, 1993.

[11] Throughout his tenure with the agency he served for Presidents Gerald Ford, Jimmy Carter, Ronald Reagan, George H. W. Bush, and Bill Clinton.

He also held the position of Special Agent in Charge of Presidential protection during the Clinton Administration, which made him responsible for the physical security of the President and First Family.

In October 2017 and again in September 2018, Merletti gave presentations in North Carolina, at Fort Bragg's JFK Center for the Special Warfare Non-commissioned Officers Academy highlighting his Special Forces training and experiences, and how he applied that training and experience to the United States Secret Service.

The 2020 Book: "They Were Soldiers" by Joseph L. Galloway and Marvin Wolf describes the contribution that Merletti made as an officeholder following his initial service as a Vietnam veteran who returned home from the "lost war".

"[16] On May 22, Chief U.S. District Judge Norma Holloway Johnson ruled that since the Secret Service employees are part of the federal law enforcement establishment sworn to assist in criminal investigations, they must testify.

In the end, Starr and his Independent Counsel were frustrated to learn that the rumor and innuendo that they had been led to believe regarding the Secret Service's involvement with the Lewinsky issue was totally unfounded.

Merletti felt vindicated and remarked, "It was the fight that mattered, future Presidents would have faith in the Secret Service's motto of being 'Worthy of trust and confidence'."

Following the September 11, 2001 attacks, Merletti was a primary driver in having the United States Secret Service designate that year's Super Bowl XXXVI in New Orleans as a National Security Special Event (NSSE) resulting in the Secret Service providing the protection plan as well as the physical protection.