Mrs. DePool (first name unrevealed) was the wife of Angus, aunt of Selbert, and grandmother of Myrna.
Hiding Selbert[]
After Selbert escaped from a mental institution and murdered Angus, Mrs. DePool hid Selbert in her home. She pretended to cooperate with Dick Tracy and the other members of the police force who were investigating her husband's murder, but was actually working to conceal Selbert's involvement. To this end, she destroyed Selbert's monogrammed sweater which he had left at the crime scene, thus eliminating a piece of evidence against her nephew.
Mrs. DePool claimed to be grateful to Selbert for killing Angus, who she described as cruel, manipulative and greedy. When the police came to her home for additional questioning, she hid Selbert under the false bottom of a cistern in her basement and denied any knowledge of his whereabouts.
Tormenting Myrna[]
The situation was complicated by the presence of Myrna, Mrs. DePool's granddaughter. Myrna's parents had died in a car accident some time previously, and she was staying in the DePool home. Mrs. DePool was initially able to keep Selbert's presence a secret, but eventually Selbert got tired of hiding and revealed himself. She threatened to call the police, and he sealed her under the cistern to keep her quiet. When Mrs. DePool discovered this, she shot Selbert in the side and freed Myrna. She enlisted Myrna in helping to care for Selbert's wound. Myrna was frightened and called for her boyfriend Revol to come for her.
Myrna did not know it, but Mrs. DePool had rigged the house's doorbell to prick the finger of anyone who pressed it with a poison needle. She did this to eliminate anyone who might come investigating. When Revol pushed the doorbell, he was poisoned and collapsed. Luckily, the house was under observation by the police, and Revol was rushed to the hospital.
Fearing discovery, Mrs. DePool removed the poison booby-trap, revealing it to Myrna. Myrna was appalled and fled the house, vowing never to return. Selbert and his aunt had a falling out, during which Selbert pushed her hand onto the poison doorbell. While she was incapacitated, Selbert stole all of the cash out her safe and set the house on fire. He fled, and Mrs. DePool died in the blaze.