First of all, Ichigo's mother is named Masaki Kurosaki and she was considered to be
a human, whereas his father was a shinigami. Furthermore, before the start of the Bleach series she was killed by the Hollow named Grand Fisher, who enjoys devouring women or children. I believe that he lured Ichigo or his mother as a bait. In addition, the girl who has recently died in the first episode of Bleach is a plus spirit and it is mentioned that her area was disturbed by a group of skateboarders. Therefore, she cannot leave the world of the living because she probably felt that she is attached to something and left something behind. After, Ichigo defeated the skateboarders he told the dead girl that he would give her more flowers since the skateboarders knocked it over where she had died and Ichigo tells her to quickly go to heaven. Later on, in the show she was chased by a Hollow named Fishbone D. I assume that he was trying to devour her soul. However, he was defeated by Ichigo and his soul was purified.