At the time he was to hold the funeral for President Vargos' late wife, Tranquil Repose had been taken over by the Great Healer. Jobel considered himself Davros' most loyal servant, mainly because Davros used hidden security cameras to watch the staff.
Takis and Lilt, two other employees, came to Jobel with a plan to get rid of Davros, and he accepted. Davros, watching this event with Tasambeker, convinced her to kill him. She didn't want to though and tried to convince Jobel that Davros wanted him dead. She tried to explain that Davros lied as freely as Jobel picked up women. He thought that that was the reason for Tasambeker's behaviour.
Her dignity insulted, Tasambeker grabbed a syringe and killed Jobel. He died on the steps of the casket dais, his wig falling off as he died, and she was exterminated soon after. (TV: Revelation of the Daleks)