Washington (CNN) -- A long-awaited federal investigation looking into allegations of a hostile work environment within the Federal Air Marshal Service concludes there is no "widespread discrimination and retaliation" within the agency, according to a report by the Department of Homeland Security's Office of the Inspector General obtained by CNN.
However, the 118-page study, triggered by CNN's coverage in 2010, did conclude that "employees' perceptions of discrimination and retaliation are extensive, and we heard too many negative and conflicting accounts of events to dismiss them."
The report is scheduled to be released to the public on February 9.
Whistle-blowers in the air marshal's Orlando, Florida, field office triggered the investigation two years ago when they alleged that supervisors fashioned a "Jeopardy!"-style whiteboard to demean and ridicule rank-and-file officers. The board contained derogatory nicknames to allude to veterans, women, Hispanics, gays, lesbians and African-Americans, they said.
The executive summary cites CNN's reporting about alleged misconduct and illegal employment discrimination within FAMS, which prompted members of Congress to call on the inspector general at DHS to review the claims not only in Orlando but throughout the agency.
The investigators conducted more than 300 interviews and site visits to FAMS offices in Orlando, Tampa, Cincinnati, Minneapolis, Charlotte and Dallas. Several dozen telephone interviews took place in field offices in seven other cities. They concluded many air marshals and some supervisors think they have been "discriminated against, fear retaliation, and believe there is much favoritism."
"There is a great deal of tension, mistrust, and dislike between nonsupervisory and supervisory personnel in field offices around the country," the report stated.
A Federal Air Marshal Service spokeswoman contacted by CNN late Thursday reiterated that the report found no evidence of widespread discrimination or retaliation, but said employees' perceptions of discrimination stem from poor communication with the work force.
"While the OLE (Office of Law Enforcement)/FAMS faces organizational challenges, the OIG notes that these challenges do not interfere with the mission of the agency," Kimberley Thompson wrote in an e-mail statement. "Through working groups, listening sessions, and advisory councils, FAMS leadership has demonstrated its commitment to improving communications within the workforce."
She added that the Transportation Security Administration "took a proactive approach to the issues raised and has developed and implemented solutions ahead of the conclusion of the investigation."
"This report is a significant vindication for air marshal whistle-blowers," said Tom Devine, legal director of the Government Accountability Project, a nonprofit whistle-blower organization. "It confirms a perceived pattern of retaliation against air marshals who challenged security breaches by Federal Air Marshal Service management."
Devine added: "The best corrective action would be to reinstate the whistle-blower who was fired, instead of fighting in court to keep him out of the government."
The government investigators said they identified factors that contributed to the allegations of a hostile work environment.
"Limited transparency in management decisions is also at the center of fears of retaliation and perceptions that management is mistreating its workforce," according to the inspector general's summary of the 21-month investigation.
The report said the TSA and the FAMS are committed to addressing the factors that led to the investigation and the problems that air marshals say still exist.
The inspector general recommended the TSA "create and implement an action plan" to address workplace issues. "The plan should include training for supervisors on communication and conflict management that is tailored to the unique Federal Air Marshal Service mission," the report stated.
The TSA concurred with the recommendation. In an OIG analysis, the report said, "The plan should include management's strategy for addressing perceptions of discrimination, retaliation and favoritism, as well as strengthening the current workplace environment, communication, diversity, reporting and addressing misconduct, and job satisfaction."
A U.S. House committee has scheduled a hearing on the Air Marshal Service for February 16.
CNN's Mike Ahlers contributed to this report.