For more than a year, FBI wiretapped labor leader John Dougherty, Councilman Bobby Henon

For more than a year, FBI agents wiretapped the cellphones of Philadelphia labor leader John "Johnny Doc" Dougherty and City Councilman Bobby Henon as part of an ongoing investigation into union corruption, according to a disclosure letter by federal prosecutors.

Prosecutors recently sent what are known as "intercept letters" to scores of people whose conversations were picked up on the wiretaps. In the letters, prosecutors also disclosed that the FBI had intercepted calls to and from the cellphones of Marita Crawford, political director for Dougherty's Local 98 of the Electricians union, and Joseph Ralston, until recently a veteran investigator with the state Attorney General's Office.

The disclosure marks the first public word that months of conversations of Dougherty and his associates are now in prosecutors' hands. The labor leader has dismissed the investigation as a groundless attack on "our union's good name."

Dougherty's lawyer, Henry E. Hockeimer Jr., declined to comment.  Henon and Crawford — still using the phone number that was tapped — did not return calls for comment. Federal prosecutors also did not return calls.

Among the many people who received the recent intercept letter was Mayor Kenney, for whom Dougherty has been an important political ally.  In confirming that the mayor was a recipient,  his spokeswoman, Lauren Hitt, said:  "I don't think it's surprising to anyone that the mayor would speak to a City Council member or the head of the building trades."

The FBI began listening to Dougherty's calls on April 29,  2015. The agents listened for a full year until news of the probe of the labor leader broke into public view — on Aug. 5, 2016, when agents searched the Local 98 union hall and the offices of Henon and Crawford.  The FBI kept the phone taps running until Aug. 26, three weeks after the raid, according to the disclosure letter.

Three and a half months after agents began listening in on Dougherty's cellphone, the FBI obtained court approval to wiretap the Democratic councilman and Crawford.

The FBI ended the four intercepts on Aug. 26, 2016, three days after agents raided Ralston's workspace at the Attorney General's Office in Philadelphia and seized his computer.

The search warrant for the raid said the FBI was interested in Ralston's work moonlighting as a security consultant and his communications with Henon. Ralston was paid for security work by Local 98 of the International Brotherhood of Electrical Workers.

The warrant also said investigators wanted to know about queries Ralston made on closely held law-enforcement databases in the Attorney General's Office.

Ralston's employment there ended Friday. A spokesman for the office confirmed Ralston's exit but would not say why he left.

Under federal rules, prosecutors are required to notify people when their conversations are picked up on wiretaps on someone else's phone. Such intercept letters are typically sent out at a late stage in an investigation, but Jeffrey Lindy, a former federal prosecutor and veteran defense lawyer in Philadelphia,  cautioned that charges, if any, could be months away given the complexity of the investigation.

Prosecutors have declared in a search warrants that they were looking at possible crimes ranging from embezzlement of union funds, tax evasion, extortion by an unnamed public official, mail and wire fraud, and the use of "economic fear" to pressure contractors.

Dougherty, 57, universally known as "Johnny Doc,"  took command of  Local 98 in 1993 and in 2015 became head of the Philadelphia Building and Construction Trades Council, which represents nearly 40 unions in Philadelphia and the suburbs.

As Local 98 chief, he has built the 4,700-member union into a potent political force, placing allies in numerous elected and appointed municipal positions, and dunning his membership to create one of Pennsylvania's biggest campaign war chests. His total compensation was $406,000 in 2015, the most recent year the union filed a required financial disclosure report with the U.S. Labor Department.

Henon, 48,  joined the union as a seasonal worker and rose through the ranks quickly, from apprentice to foreman to business agent. He gained a spot as Dougherty's right-hand man and became the union's political director in 1999. His staff said Monday that he was not in his City Hall office.

He is serving his second four year-term after joining Council in 2012. He became majority leader at the start of his second term.

Henon remains on the union's payroll in an untitled position that reports directly to Dougherty, making $71,711 last year in 2015. That is on top of the $138,890 he makes as a Council member.

Crawford, 47, succeeded Henon as the union's political director.  Her union compensation in 2015 was $166,500.

In the August 2016 raid,  FBI and IRS agents searched Dougherty's home and his union office on Spring Garden Street. They carted off more than 100 boxes of documents, along with several computers.

The same day, the agents searched Henon's City Hall office and his district office on Torresdale Avenue. Agents also searched the home of Crawford, who also lives in Philadelphia.

Nearly a year after the FBI first began tapping Dougherty as part of the federal investigation, the state Attorney General's Office began its own investigation of the labor leader.

The agency began using a grand jury to look into Dougherty and his union after an incident in Philadelphia in January 2016 in which Dougherty got into a brawl with a non-union electrician.  However, the state probe seems to have come to a halt.

Joseph Grace, the spokesman for the Attorney General's Office, declined to talk about the investigation in any detail, but did say: "We are assisting the U.S. Attorney's Office and deferring to the federal investigation."

The recent intercept letter, reviewed by the Inquirer and Daily News, was dated May 15 and signed by two of the three assistant U.S. attorneys assigned to the Dougherty investigation, Frank R. Costello and John Gallagher.

Costello, 62, is a 30-year veteran of the office who was a key player in prosecutions of charter-school fraud and schemes to sell drugs illegally over the internet. Gallagher, 51, earned his law degree at night working as a New York police officer in the Bronx. A one-time adviser to former Philadelphia Police Commissioner John F. Timoney, Gallagher's work as a federal prosecutor included obtaining a death-penalty verdict against Kaboni Savage, a drug kingpin linked to a dozen murders.

A  third veteran prosecutor, Paul L. Gray, 62, completes the team in the Dougherty inquiry. Among other headline-making cases, Gray led the successful corruption prosecution of former U.S. Rep. Chaka Fattah.

He was also involved in a previous probe that led to a guilty plea from a Dougherty associate, electrical contractor Donald "Gus" Dougherty Jr., who is not related to the labor leader.  That probe also investigated John Dougherty, but no charges were brought.

In 2008, Donald Dougherty was sentenced to two years in prison after he pleaded guilty to charges that included avoiding making $1 million in required contributions to the union's employee benefits plan.

He also pleaded guilty to providing $115,000 worth of free renovations on the home of John Dougherty. But he did not agree to be a witness against the labor leader.

After the plea, a union spokesman said John Dougherty had not been party to any free work and had never agreed or expected to pay anything other than a fair price.