With the news of Bob Ley retiring from ESPN, Mike Greenberg reflects on what Ley has meant to the company and calls him "the conscience of ESPN." (1:06)

Bob Ley, after a 40-year career at ESPN, announced his retirement from the network Wednesday.

Ley, who had taken a leave of absence in October, said in a statement that he will be retiring at the end of this month. He was ESPN's longest-tenured anchor.

"To be clear, this is entirely my decision," Ley said. "I enjoy the best of health, and the many blessings of friends and family, and it is in that context that I'm making this change."

Ley, 64, thanked ESPN president Jimmy Pitaro and the network's senior leadership team "for their understanding and patience over the past months."

Too many folks to thank individually, right now, but know that I have you all in my mind and my heart. Some news to share: pic.twitter.com/Qydhpcy4MV — Bob Ley (@BobLeyESPN) June 26, 2019

"Through the decades, and my innumerable experiences at ESPN, I have built many deep and fulfilling friendships. You know who you are. I hope you also know how much you mean to me. We have shared an American story unlike any other. And we will continue to do so in the years ahead," Ley said.

"I have been gifted by our viewers and consumers with a precious commodity -- your trust. To be invited into your homes was a privilege I never took for granted, one I worked each day to uphold. Thank you for that.

"In September, I signed off my last show saying, 'I'll catch you on the flip side.' Now it's time to take that vinyl off the turntable (ask your folks), flip it over, and drop the needle on the B-side. There are always great cuts, and hidden gems on the B-side.

"Thank you for a great run."

Ley joined ESPN as a SportsCenter anchor on Sept. 9, 1979 -- the third day of the network's operation. In 1980, he hosted the first NCAA selection show and live broadcast of the NFL draft and continued in that role for the next nine years.

He was the host of Outside The Lines, ESPN's investigative news program, since the show launched in May 1990 and also hosted ESPN's weekly E:60 show on Sunday mornings, leading the coverage of several important stories. As host of OTL, Ley was a leader in reporting on concussions and chronic traumatic encephalopathy and the NFL's handling of domestic violence cases.

"Bob has been our North Star and always kept us going in the right direction,'' longtime ESPN broadcaster Chris Berman said. "He kept us honest. When you watched him you knew what you were getting and you were getting it straight.

"I know he is very at ease and at peace with his decision. He's earned it.''

Ley joined Jeremy Schaap on Wednesday's episode of Outside the Lines.

Norby Williamson, executive vice president of event and studio production, said in a statement that Schaap and Ryan Smith "will handle the bulk of anchoring duties" for OTL going forward.

Ley won 11 Sports Emmy Awards during his time at ESPN, including an Emmy for outstanding studio host in 2018. Ley and OTL won the DuPont Award in 2014 for reporting on issues in football at the youth level. Ley and OTL also won four Edward R. Murrow Awards.

"The standard of excellence that has become a hallmark of ESPN began in the early days when we were a startup with a bold vision," Pitaro said in a statement. "Bob was there for all of it and, over the years, his unwavering commitment and unparalleled work ethic drove our journalistic ambitions. The best way we can thank Bob for what he's meant to ESPN and to sports fans is to continue to uphold the journalistic integrity and principles he's instilled in ESPN for nearly 40 years."

Ley was inducted into the National Sports Media Association Hall of Fame earlier this week. He told The Associated Press he plans to work with Seton Hall University, his alma mater, in retirement as well as continue to mentor young journalists.

Information from The Associated Press was used in this report.