Kamainen, Juta

From Srafopedia

Juta Kamainen is a young witch (100 years old), and her Dæmon is an unnamed Robin. She's stubborn and has a colorful style.

She's one of the twenty Latvian witches who joined together under Serafina's command in a mission to protect Will and Lyra in their journey. Juta fell in love with Stanislaus Grumman and he rejected her. As a result her love soured into a terrible hate and she swore to kill him the next time she saw him.

In the last chapter of "The Subtle Knife", she finds him talking to Will and she shoots him dead with an arrow. After that she kills herself by stabbing herself in the chest with a knife.