Section 9B. No person permanently employed in any institution under the department of mental health, developmental services, public health, public welfare, correction or youth services, or in the soldiers' homes in Massachusetts, except an employee, other than a nurse, rendering professional service, who is not classified under chapter thirty-one, and no maintenance employee permanently employed in any institution under the department of education, shall, after having actually performed the duties of any office or position continuously for a period of six months in such an institution or department, be discharged, removed, suspended, laid off, transferred from the latest permanent office or employment held by him without his consent, lowered in rank or compensation, nor shall his office or position be abolished, except for just cause and in the manner provided by sections forty-one to forty-five, inclusive, of chapter thirty-one.

It shall be deemed that there is just cause to discipline or discharge an employee of the commonwealth, if it is determined by a preponderance of the evidence that such employee abused a person with a disability in the care of the commonwealth, including but not limited to the department of mental health, department of developmental services, department of public health, department of children and families, department of corrections, department of youth services, department of education and Bridgewater state hospital. For the purposes of this section, abuse includes, but is not limited to, the following:

(1) any non-accidental act or omission that results in physical or emotional injury to the disabled person;

(2) non-accidental, unauthorized physical aggression;

(3) verbal harassment; and

(4) sexual harassment.

In any disciplinary proceeding pursuant to this section, chapter thirty-one or chapter one hundred and fifty E, the report of an investigation of abuse shall be admissible into evidence for the truth of the matters asserted therein. The credibility of any witness or the veracity of any witness' statements given at such a disciplinary proceeding may not be challenged solely on the basis of his disability.