William F. Reckert, 77, who died April 1 of congestive heart failure at his home in Springfield, spent more than 50 years literally dotting the i’s and crossing the t’s for Justice Department investigations, including the Watergate special prosecution team.

He spent untold hours listening to tape recordings of undercover agents, making his own recordings of court or conference testimony and then transcribing them into flawlessly typed documents. His job title was “closed microphone reporter.”

A closed microphone reporter, his son said, was someone who sat in on official proceedings and repeated the official testimony verbatim into a recording mask. Later, the recordings were transcribed at a typewriter or computer. The job required unwavering attention, precise enunciation, many stops and starts at the keyboard and unfailing accuracy. Mr. Reckert, who was born blind and remained sightless throughout his life, was known for turning in letter-perfect work.

“He sent me a letter a week, typed on an IBM Selectric typewriter, when I was away at boarding school,” said his son, Bill Reckert. “In nine months, he had one spacing error.”

Born in Westminster, Md., Mr. Reckert grew up in Georgetown. He attended the Maryland School for the Blind in Overlea and received a bachelor’s degree in business administration from Georgetown University, where he was on the wrestling team. At the time, collegiate wrestlers competed in the Greco-Roman style, which required a standing start. The referees’ single concession to Mr. Reckert’s blindness was to allow competition to start on the floor.

Mr. Reckert began his career in the federal government in 1951 as a medical transcriber for the Veterans Administration, moving to the Justice Department five years later. When he retired with 53 years of federal service, a year and a day before his death, he had accumulated 5,500 hours of unused sick leave, which his son said he donated for use by other federal employees.

His work included projects for U.S. Attorney General Robert F. Kennedy, witness interrogations for the Justice Department’s civil fraud division, the antitrust division’s IBM case and the Watergate special prosecution team.

His family said he discovered the infamous 18 1/2- minute gap as he typed the June 20, 1972, secret recording of an Oval Office conversation between President Richard Nixon and chief of staff H.R. Haldeman.

“Dad thought there was a fault with the [transcribing] equipment and called a guard in,” his son said. “When he found out there had been no power or equipment failure, they called [special prosecutor Leon] Jaworski’s office. They kept him there, and he wasn’t allowed to communicate with our family until they sent him home about 3 or 4 o’clock that morning in a big, black limousine.”

“He talked about it very, very infrequently,” the son said. “It was only later in life when we said, ‘C’mon, you were working on the White House tapes that night,’ that he said, ‘Well, enough time has passed that I guess it’s all right.’ He was like the anonymous government employee, the courier who picked up the tapes, or whatever. Mom said the night they brought him home, he was white as a sheet.”

After a 1977 FBI investigation into price-setting by Michigan hearing-aid dealers, Mr. Reckert was asked to transcribe tapes. He endured exhaustive direct and cross-examination by defense counsel who attacked his professional expertise before the 120-page transcript was entered into evidence.

“He never liked to let anyone think he used his blindness to his advantage,” his son said. He had a part-time job for several years typing medical discharge summaries at Children’s Hospital, and his wife drove to the hospital to pick him up the night of the April 1968 riots in Washington because he couldn’t take public transportation and didn’t want to ask for favors from co-workers.

His power of memory was legendary in his family -- he could remember account numbers for bank records, phone numbers and birthdays for years. He did all math in his head, and when using Braille, he punched out the codes from right to left, then flipped the paper over to read it from left to right.

Mr. Reckert was a weekly participant for more than three decades in Project Venture at the Washington YMCA. He also was a member of Ski For Light, a cross-country skiing program for handicapped individuals, and he followed an exhaustive exercise regiment involving swimming, walking, weight training and cycling. He also had a lifelong love of classic radio programs, which he collected on almost 600 audiocassettes.

His wife of 50 years, June M. Reckert, died in 2000.

Survivors include his son, Bill, of Sterling; a daughter, Pam George of South Riding; three brothers, Joe Reckert of Round Hill, Bob Reckert of Bowie and David Reckert of Rockville; three sisters, Eileen Heim of Bethesda, Virginia Ann Lapp of Gaithersburg and Maysie Pettit of Fort Myers, Fla.; and four grandchildren.