( CNN ) -- Five-year-old Jeremiah Oliver was last seen by his Massachusetts relatives on September 14 . But the investigation into his disappearance did n't begin until last week when the authorities were first alerted to it . Now , the child is feared dead , his mother and her boyfriend are in custody , and everyone is left wondering how a child could simply vanish unnoticed for three months . How could this happen , especially to a child who was supposed to be receiving monthly visits from a state-provided social worker ? Turns out , tragically , Jeremiah was not getting the visits , state officials say . Who 's to blame ? The finger pointing , demands for accountability and calls for investigations are reverberating throughout the state . `` This is a deeply concerning case of neglect and abuse , '' said Olga Roche , commissioner of the Massachusetts Department of Children and Families . The state agency was charged with the responsibility of protecting children from child abuse . Roche called the situation `` a serious failure '' and put the blame squarely on the shoulders of the boy 's social worker and supervisor , both of whom were quickly fired . `` The social worker assigned to this case did not conduct the required in-person , monthly checks on the family , '' Roche said in a statement . `` And the supervisor failed to enforce that policy . '' Neither the social worker nor the supervisor have been named , but their union spokesman says they have been made `` convenient scapegoats '' at an overwhelmed agency . `` We are disappointed that Commissioner Roche is more interested in finger-pointing than accepting responsibility for yet another tragedy on her watch , '' said Jason Stephany of the Service Employees International Union Local 509 , which represents caseworkers at the Department of Children and Families . `` Instead , the Commissioner has chosen a convenient scapegoat to deflect blame from department administrators . '' More blame to go around . But Gov . Deval Patrick hinted Friday that they might not be the only two held accountable . `` I 've asked the Commissioner to look into the question about whether responsibility goes beyond those two , '' he said in an appearance on Boston Public Radio . `` I have some reason to believe it does . '' The last documentation of an interaction with Jeremiah was in May , according to Department of Children and Families spokesman Alec Loftus . In June , Loftus says the social worker was told that Jeremiah had moved to Florida to live with his grandmother , but never bothered to follow up or verify whether that was the case . The last time a visit to the home occurred was in November , at which Loftus says the social worker left behind a business card indicating that this would be DCF 's final visit . Just days later , on December 2 , Jeremiah 's 8-year-old sister disclosed to counselors at her elementary school that her mom 's boyfriend , Alberto Sierra , 22 , had abused her , according to a police affidavit . Multiple calls to Sierra 's attorney have gone unreturned . `` As a result of those statements '' the affidavit continues , `` [ she ] and [ another brother that is n't Jeremiah ] were removed from the home and taken into protective custody . '' When cops asked Elsa Oliver , 28 , where her third child Jeremiah was , she told them that he had moved to Florida , a law enforcement source involved in the investigation told CNN . This time , however , she was going to have to prove it . Where is Jeremiah ? Oliver went before a state juvenile judge at a hearing on December 13 , where she was `` observed to have bruises , disheveled hair , and appeared to have been assaulted , '' according to court documents . She refused to divulge Jeremiah 's whereabouts , according to the source . The judge ordered her to produce the child within 72 hours . The time passed with no sign of Jeremiah . Oliver was arrested . The mother has been charged with two counts of reckless endangerment of a child and two counts of accessory after the fact of a felony ( assault and battery with a dangerous weapon ) , according to a statement from Worcester County District Attorney Joseph Early . A plea of not guilty was entered on her behalf . Those charges may not necessarily pertain to Jeremiah and more details could emerge at a December 24 hearing , a spokesman for the district attorney 's office said . Elsa Oliver 's attorney , James Gavin Reardon , was n't able to elaborate either . `` I met with her for 10 hours and was unable to obtain any significant information '' Reardon said , prompting him to seek a mental health evaluation to determine whether she was even competent enough to stand charges . He says that evaluation is currently underway . Sierra , meanwhile , is charged with two counts of assault and battery with a dangerous weapon and two counts of assault and battery on a child causing bodily injury , according to the district attorney 's office said . A plea of not guilty was also entered on his behalf . He also has a hearing scheduled for December 24 . For now , authorities are holding out hope that Jeremiah might be out there somewhere , and they 're asking anyone who might know anything to call the Massachusetts State Police .
Jeremiah Oliver was last seen in London . The year - old is still missing . The young girl 's father and boyfriend have been murdered . ` ` This is a deeply concerning case of neglect , '' commissioner says .