Bertha Jorkins knows a secret, and it gets her killed. Although Bertha seems quite scatterbrained to her coworkers at the Ministry of Magic, she has “an excellent memory for gossip,” according to Sirius Black, and a difficult time keeping her mouth shut.
That's why Barty Crouch Sr. has to do something drastic when Bertha visits his home one day and discovers that Barty Crouch Jr. is hidden there. Barty Jr., a servant of Voldemort, has been convicted of crimes against the wizarding community, especially torturing the Longbottoms, and is supposed to be in Azkaban, but his parents help him escape. His father keeps careful control over him, but the house elf Winkie begs some favors, including letting Barty Jr. go without his invisibility cloak now and then. That's why Bertha sees him. Barty Sr. knows all about Bertha's penchant for gossip, and he places a strong memory charm on her, a charm so strong that it makes her more scatterbrained than ever.
While on vacation, Bertha has a highly unexpected meeting with an old schoolmate, Peter Pettigrew. Peter decides that Bertha might know something important, and he takes her to his master, Voldemort, who remains hidden in an Albanian forest. Voldemort breaks Barty Sr.'s memory charm and extracts the information he desires: his most faithful servant, Barty Jr., is still alive and no longer in Azkaban. The powerful dark magic Voldemort uses on Bertha damages her, and he unceremoniously kills her when she is of no more use to him.