(CNN) -- The head of the Massachusetts Department of Children and Families resigned Tuesday following the deaths of three children the agency was charged with protecting.
The resignation of Olga Roche, who has more than three decades in child welfare, comes after state lawmakers and the public called for the embattled commissioner to step down after the deaths of 5-year-old Jeremiah Oliver, 4-week-old Aliana Lavigne, and 2-week-old Bailey Irish.
"For DCF to move on ... there must be accountability for the tragedies," Gov. Deval Patrick told reporters Tuesday. "That's the only way the agency earns the public's confidence."
Patrick, who named Roche acting commissioner in April 2013 and permanently appointed her in October 2013, expressed faith in Roche, but said the controversy over the recent deaths of the two infants and the disappearance of a toddler whose body was later found made it impossible for her to stay.
The deaths have sparked outrage. On Monday, House Speaker Robert DeLeo, Senate President Therese Murray and Attorney General Martha Coakley all demanded Roche's resignation.
"The vast majority of the time, DCF gets it right," Health and Human Services Secretary John Polanowicz told reporters. "Sometimes, no matter how diligent or carefully a family is supervised, a tragedy can happen."
Polanowicz said he accepted Roche's resignation "because I believe it is not possible for the agency to move forward in this environment with her at the helm."
In a statement, the Massachusetts Human Service Workers Union, SEIU Local 509, said the change at the helm represented a "critical opportunity" to institute reforms and investments in the agency.
Members of the union, which represents social workers, investigators, supervisors and more than 17,000 other human service workers and educators throughout the commonwealth, took to the streets last week in a protest demanding the hiring of more social workers.
"At DCF, we face a caseload crisis that worsens each day," chapter President Peter MacKinnon said in a statement. "Policy changes and accountability measures are desperately needed. Communication barriers and outdated technology continue to slow our efforts in the field."
Erin Deveney, former chief of staff at the Massachusetts Department of Transportation, was named interim commissioner.
Roche, who did not attend Tuesday's press conference, was not immediately available for comment.
Patrick said Roche, despite her experience, "can no longer command the trust of the public or the confidence of her line staff."
A day earlier, a visibly angry Patrick described the death of Aliana Lavigne as "intolerable" after learning that social workers misplaced a police officer's faxed complaint about the suspected neglect of the infant, according to CNN affiliate WCVB. Aliana was dead by the time a social worker investigated.
"I'm upset as anyone about the loss of these children," Patrick said. "My confidence in the whole organization has been rattled."
Police told WCVB that officers filed a written report of suspected abuse or neglect -- known as a 51A -- after a visit to the home of Andrea Lavigne on April 3. But DCF officials said the officers did not follow up with a phone call as required by law. The fax was discovered days later. Police officials insisted officers did what they were supposed to do.
Lavigne stopped breathing April 11 while sleeping in her mother's bed, WCVB reported. The case was assigned to a social worker one day before the child's death.
Earlier this month, the body of 5-year-old Jeremiah Oliver was found off a highway in central Massachusetts after a seven month search, WCVB reported. His family was under DCF supervision at the time of his disappearance.
Authorities said 16-day-old Bailey Irish was brought to the hospital on Saturday morning by her parents, who were under DCF supervision. She was pronounced dead a short time later.