Question: How was one of the Mercury Seven who later became NASA's first Chief of the Astronaut Office?

Context paragraphs:
Robert L. Behnken: Robert Louis "Bob" Behnken (born July 28, 1970 in Creve Coeur, Missouri) is a United States Air Force officer, NASA astronaut and former Chief of the Astronaut Office.  Behnken holds a Ph.D in Mechanical Engineering and holds the rank of Colonel in the U.S. Air Force.  Col. Behnken has logged over 1,000 flight hours in 25 different aircraft.  He flew aboard Space Shuttle missions STS-123 and STS-130 as a Mission Specialist, accumulating over 378 hours in space, including 19 hours of spacewalk time.  Behnken was also assigned as Mission Specialist 1 to the STS-400 rescue mission.  He is married to fellow astronaut K. Megan McArthur.

Janet L. Kavandi: Janet Lynn Kavandi, a native of Carthage, Missouri, (born July 17, 1959) is an American scientist and a NASA astronaut.  She is a veteran of three Space Shuttle missions and has served as NASA's Deputy Chief of the Astronaut Office.

Ellen S. Baker: Ellen Louise Shulman Baker, M.D., M.P.H. (born April 27, 1953) is an American physician and a NASA astronaut.  Baker serves as Chief of the Education/Medical Branch of the NASA Astronaut Office.

Steven Lindsey: Steven Wayne Lindsey (born August 24, 1960) is a retired U.S. Air Force officer and NASA astronaut.  Lindsey served as Chief of the NASA Astronaut Office from September 2006 until October 2009.

Mercury Seven: The Mercury Seven were the group of seven Mercury astronauts announced by NASA on April 9, 1959.  They are also referred to as the Original Seven or Astronaut Group 1.  They piloted the manned spaceflights of the Mercury program from May 1961 to May 1963.  These seven original American astronauts were Scott Carpenter, Gordon Cooper, John Glenn, Gus Grissom, Wally Schirra, Alan Shepard, and Deke Slayton.

Mercury 13: Mercury 13 refers to thirteen American women who, as part of a privately funded program, underwent some of the same physiological screening tests as the astronauts selected by NASA on April 9, 1959 for Project Mercury.  The term was coined in 1995 by Hollywood producer James Cross as a comparison to the Mercury Seven name given to the selected male astronauts; however, the Mercury 13 were not part of NASA's astronaut program, never flew in space and never met as a group.

Chief of the Astronaut Office: The Chief of the Astronaut Office is the most senior leadership position for active astronauts at the National Aeronautics and Space Administration (NASA).  The Chief Astronaut serves as head of the NASA Astronaut Corps and is the principal advisor to the NASA Administrator on astronaut training and operations.

The Cape (1996 TV series): The Cape is an American dramatic TV series, with elements of science fiction, action/adventure, and drama, that was produced for syndication during the 1996–97 television season.  "The Cape" told the story of select members of the NASA Astronaut Corps at the Kennedy Space Center in Florida with a focus on their personal lives as they train for, and execute, Space Shuttle missions.  The series stars Corbin Bernsen as USAF Colonel Henry J. "Bull" Eckert, an experienced astronaut who, early in the series, was the Director of Astronaut Training but later in the series was also tasked with the responsibility of Chief of the Astronaut Office.

Deke Slayton: Donald Kent "Deke" Slayton (March 1, 1924 – June 13, 1993), (Major, USAF) was an American World War II pilot, aeronautical engineer, test pilot who was selected as one of the original NASA Mercury Seven astronauts, and became NASA's first Chief of the Astronaut Office.

Christopher Cassidy: Christopher John "Chris" Cassidy (born January 4, 1970, in Salem, Massachusetts) is a NASA astronaut and United States Navy SEAL.  Chris Cassidy achieved the rank of Captain in the U.S. Navy.  He was the Chief of the Astronaut Office at NASA from July 2015 until June 2017.

Supporting paragraphs: Mercury Seven Deke Slayton
Answer: Deke Slayton