An American mother has been charged with murder after her two young children were found hanging in the basement of their home in Pennsylvania, prosecutors said. Lisa Snyder, 36, claims that her eight-year-old son and four-year-old daughter had committed suicide because the boy was being bullied at school."This is a horrific, tragic incident," Berks County district attorney John Adams told reporters on Monday shortly after Snyder was arrested.Snyder's arrest comes two months after Conner and Brinley Snyder were found close to death in the small town of Albany Township, 68 miles north of Philadelphia.On September 23, Snyder, who was raising the children alone, called 911 to say she had found them hanging in the basement.Emergency services discovered them hanging from a beam by a dog leash with two chairs lying on their sides nearby.They tried to revive them but the children were declared dead three days later.Snyder told police that Conner was being bullied at school and "wanted to die." "Eight-year-olds, generally, that I am aware of, do not commit suicide, so of course we had questions," Adams said.He added that interviews with the school and relatives found no evidence of bullying.An inspection of Snyder's mobile phone and computer found searches related to hanging and carbon monoxide asphyxiation, the prosecutor said.Snyder, who is being held without bail, has been charged with two counts of first degree murder and evidence tampering. She has also been charged with one count of sexual intercourse with an animal, among other charges.Social services removed the children from Snyder's custody a few years ago but they were returned to her in February 2015, Adams said.