This could be the snake that bit her.

Katherine Field was the third CHERUB agent to be killed during a mission. Her mission was based in India were she was bitten by a venomous snake she managed to get to the hospital but the species was wrongly identified so she was given the wrong antivenomm - she died because of it.

This made her the first female agent to be killed during a mission,

Age Unkown
Sex Female
Cause Of Death Snake bite
Status KIA (Killed In Action)