Cops: Grandma says she has "surprise," stabs grandson, 6

Martha White, 63, is arrested on first-degree murder charges after allegedly stabbing her grandson to death

CBS affiliate WCTV

TALLAHASSEE, Fla. - A Florida grandmother accused of murdering her 6-year-old grandson allegedly told him she had a "surprise" for him before stabbing him to death, reports CBS affiliate WCTV.

Martha White, 63, is charged with first degree murder after allegedly stabbing Mason Rhinehart to death in her bathroom on Tuesday. According to arrest papers, White told the child she had a "surprise" for him before the alleged attack.

Mason's brother, Aiden Rhinehart, 8, was outside the locked bathroom door during the alleged murder. According to arrest papers, he could hear his younger brother screaming, "Don't kill me, Grandma! I don't want to die!"

Zack White, the boys' father, reportedly says Aiden called him to tell him about the incident and he instructed the boy to pound on the door and scream his brother's name. When there was no response from the 6-year-old, Zack White said he told his son to hide.

Arrest papers say Aidan told detectives he saw his grandmother leave the house with a bottle of wine in her hand and told him she had a surprise for him too.

Deputies say they tracked her down at a nearby park. Arrest papers indicate she was covered in blood and had wine and Xanax with her.

A Leon County Sheriff's Office spokesman says investigators are still trying to pinpoint a motive.

Martha White told police who arrested her she was "fed up" with the boys' mother, according to arrest papers. She is being held in jail without bond. Prosecutors say the case will now go to a grand jury for review.