By Henry Moore A Missouri man has claimed he mistook his mum for an intruder before shooting her to death in their home. Jaylen Johnson has been charged with manslaughter and armed criminal action in connection with the death of his mother, Monica McNichols-Johnson, on Thursday. The 25-year-old’s lawyer, William Goldstein, told the St Louis Post-Dispatch that Johnson had wrongly believed his mum was a burglar when she entered the St Louis home at 7:30am last Thursday. Police said Monica, 56, died at the scene despite efforts by Johnson’s girlfriend to help after the shooting. Johnson, who rema…