(a) The Commissioner of Children and Families shall file a petition to terminate parental rights pursuant to § 17a-112 if (1) the child has been in the custody of the commissioner for at least fifteen consecutive months, or at least fifteen months during the twenty-two months, immediately preceding the filing of such petition; (2) the child has been abandoned as defined in subsection (j) of § 17a-112; or (3) a court of competent jurisdiction has found that (A) the parent has killed, through deliberate, nonaccidental act, a sibling of the child or has requested, commanded, importuned, attempted, conspired or solicited to commit the killing of the child or a sibling of the child; or (B) the parent has assaulted the child or a sibling of a child, through deliberate, nonaccidental act, and such assault resulted in serious bodily injury to such child.

(b) Notwithstanding the provisions of subsection (a) of this section, the commissioner is not required to file a petition to terminate parental rights in such cases if the commissioner determines that: (1) The child has been placed under the care of a relative of such child; (2) there is a compelling reason to believe that filing such petition is not in the best interests of the child; or (3) the parent has not been offered the services contained in the permanency plan to reunify the parent with the child or such services were not available, unless a court has determined that efforts to reunify the parent with the child are not required.