At The Burrow, Percy Weasley mentions that Bertha has been missing for over a month, having never returned from her holiday in Albania. According to Ludo Bagman, Bertha has got lost on many other occasions, and has always returned. He maintains that she probably misread the map and ended up in Australia instead of Albania.
At the campsite, Ludo Bagman tells Arthur that there still hasn't been any word from Bertha. Ludo is certain that she will turn up soon, remarking that the witch has a memory like a leaky cauldron, and has no sense of direction. He is certain that she will wander back into the office some time in October, convinced it is still July.
Bertha Jorkins was a few years above Sirius Black and James Potter at Hogwarts. Sirius tells Harry that Bertha was an idiot when he knew her; she was very nosy, but had no brains at all. He thinks she would be very easy to lure into a trap, and is worried that Bertha went missing in the area Voldemort was last rumoured to be.
Sirius says that the Bertha Jorkins he knew at school wasn't forgetful at all - quite the reverse. She was a bit dim, but had an excellent memory for gossip. She used to get into a lot of trouble because of this, as she never knew when to keep her mouth shut.
A shadowy form of Bertha Jorkins appears from Voldemort's wand as the effects of Priori Incantatem occur. She surveys the battle before her with wide eyes, and tells Harry not to let go of his wand, and not to let Voldemort get to him. She paces around the inner walls of the golden web with the shadows of Cedric Diggory and Frank Bryce. When Harry breaks the bond between his and Voldemort's wand, the shadowy figures of Voldemort's victims close in upon Voldemort, shielding Harry from his gaze.
Barty Crouch Junior reveals that Bertha discovered his secret when visiting Mr Crouch's house one day. She overheard Winky talking to Barty Crouch Junior, and went to investigate. She heard enough of the conversation to guess who was hidden under the Invisibility Cloak, and confronted Mr Crouch when he arrived at the house. Bertha was placed under a very powerful Memory Charm by Mr Crouch, so powerful that it damaged her memory permanently.
Bertha was captured in Albania by Voldemort. She was tortured by the Dark Lord, and told him a great deal of information as a consequence. She revealed that Alastor Moody was going to teach at Hogwarts during Harry's fourth year, and about the Triwizard Tournament. Bertha was tortured with such severity that it broke through the Memory Charm placed on her by Mr Crouch, and she was able to tell Voldemort that Barty Crouch Junior was still alive. She told him that Mr Crouch was keeping his son imprisoned to prevent him from seeking Voldemort out.