DENVER — What caused nearly every employee of the Boulder Museum of Contemporary Art to resign en masse last week? Was it a difficult museum boss who staffers say worked them to the point of exhaustion for low wages and treated them with little respect? Or was it the result of a plan that backfired — a plan hatched by a handful of disgruntled workers who, as Ron McMahan, a board member, put it, tried to “take over” control of the institution?

The museum and its ex-employees are offering starkly different accounts as the museum is reeling after losing five full-time staffers, at least two part-time visitor-services workers, and seven contract support staff and educators on June 13. The museum, in Boulder, Colo., remains open and some emergency help has been brought on, but maintaining the exhibitions and public programming will be a challenge, said David Dadone, the executive director.

The dispute dates to March 11 when five staff members sent a letter to the board accusing Mr. Dadone of misdirecting funds intended for educational programs, failing to deliver on programs promised to donors, violating labor laws and engaging in a pattern of abusive behavior toward subordinates. “How many organizations expect employees to work for 10- to 12-hour shifts without even a single 15-minute break,” Nora Lupi, the former visitor services and membership manager, wrote in her resignation letter, which was sent to The New York Times. “How many institutions expect someone who makes less than $14/hr to be on call 24/7 for operational, managerial and executive assistant demands?”

But the board contends that it investigated the allegations, going so far as to hire a lawyer, Gwyneth Whalen, a former Boulder County District Court judge now in private practice, to examine the charges. Her report, conducted through interviews over several months, concluded on June 6 that “there is no basis to the allegations concerning labor law violations and mistreatment of staff,” according to a statement on Monday by the board.