Tel Aviv municipal social workers were stunned on Wednesday as reports continued to come in about the murder of four-year-old Michael Kruchkov the previous night by his mother, Regina. Police arrested the mother with murder after paramedics arrived at her south Tel Aviv apartment to find the boy's lifeless body. She later told investigators she had drowned her son in the bath. "Our most recent report from May, only a few months ago, describes the boy as a happy and well cared for child, with a very good interaction with his mother," Hassia Netter, director of south Tel Aviv's Social Welfare Department, told The Jerusalem Post. "Even with all my 30 years experience in this field I cannot explain how this happened." Netter said that Regina, who immigrated to Israel 11 years ago and lived close to her ailing parents, was a single working mother who had turned to the department two years ago for help in obtaining a state-subsidized place at a city day care facility for Michael. She also said that Michael's father, who had never been married to his mother, had behaved violently toward Regina and that the two had split up a number of years ago. "We did not label Michael as a child-at-risk, even though he had some mild speech problems," said Netter, adding that the boy had recently started in a special needs kindergarten at the nearby Bloch Elementary School. "When we assess each family, we look at several factors," she said. "We evaluate the mother's emotional status and her interaction with the child. We then consider outside stresses, too. If a mother is unable to care sufficiently for her child then we will refer the family to child protection officers." She added, however, "We have no way of knowing the inner feelings of a person. We can only look at the external signs. If a person is continuing with life as normal and nothing seems out of place, how can we know that something is wrong on the inside?" According to Netter and her colleague Sandra Kuliok - Regina and Michael's case worker - the family had not given off any "alarm signals." It is not always easy for people to predict extreme behavior, said Prof. Hanoch Yerushalmi, a lecturer in Community Mental Health at the University of Haifa who is not directly connected to the case. He said parents who were driven to murdering their child usually combined two distinct factors - a deep emotional or mental disorder and outside stress that could trigger such extreme behavior. "The person loses their grip on reality, not allowing them to be able to judgment what is right and wrong," Yerushalmi told the Post. "If there are outside stresses, too - a single parent or a child with certain special needs - this can push them to commit such an act." Nurit Kaufman, director of the Violence against Women department at the Women's International Zionist Organization, which runs the National Hotline for Battered Women and Children at Risk, said most studies into why a mother would kill a child had not been able to pin-point a particular stereotype. "Sadly, there is no clear sign as to who would do something like this," Kaufman said. "Such people come from all types of backgrounds, religious and ethnic make-up and socioeconomic status, it makes no difference." The Kruchkov case is the third such incident to come to light in the past two weeks. Last week Olga Borisov of Rishon Lezion admitted to murdering her son, Alon Yehuda, four, at a Bat Yam beach, and details about Rose Pizem, four, from Netanya, being allegedly murdered by her grandfather Ronnie Ron were also released to the public.