Bartemius
"Barty" Crouch, Sr was the
head of the Department of Magical Law Enforcement when Lord Voldemort
first came to power. He became as ruthless as some on the Dark Side,
and gave Aurors powers to kill rather than capture suspected Death Eaters
who resisted arrest. He sent Sirius Black to the wizard prison Azkaban
without a trial. Crouch appeared to be the favourite to become the next
Minister for Magic, when his own son, Barty Crouch Jr, was caught with
Death Eaters who were trying to bring Voldemort back to power. Crouch
gave his son a trial before sending him to Azkaban; however, according
to Sirius, the trial was a sham, merely a public demonstration of how
much he hated the boy.About a year after the trial, Crouch's terminally ill wife begged for her son's life to be saved, so Crouch gave her Polyjuice Potion that made her take on her son's appearance while their son drank some that caused him to take on his mother's appearance, and thus escape Azkaban. After the supposed death of his son in prison, public sympathy fell on Crouch Jr; the wizarding world placed all the blame on Crouch Sr, accusing him of driving his son to join the Death Eaters because of his neglect of his family. After the scandal, Crouch lost much of his popularity and he was shunted sideways to a post as the head of the Department of International Magical Co-operation.
Barty Crouch Senior makes his first appearance in the series at the Quidditch world cup in Harry Potter and the Goblet of Fire. Crouch accuses Harry Potter of attempting to set off the Dark Mark, and when Winky is found to have Harry’s wand, he angrily dismisses Winky, as the house-elf was supposed to look after his son who was always under an Invisibility Cloak. Voldemort and his servant Wormtail showed up at the Crouch family home and put Barty Crouch under the Imperius Curse, freeing Crouch Jr from the Imperius Curse placed on him by his father and thus rejoining Voldemort. Crouch continues to appear in public at first and is one of the five judges at the Triwizard Tournament, attempting to judge the contestants fairly. However, worried that Barty Crouch would fight the Imperius Curse, Voldemort later kept him imprisoned within the house and had him communicate exclusively through supervised owl post. Percy Weasley, who had become Crouch's loyal aid and was known to Crouch as Weatherby, replaced him as the British's Ministry's representative on the Triwizard judging panel.
Later Crouch Sr, who had escaped from his home, meets Harry Potter and Viktor Krum in the Forbidden Forest and begs to see Dumbledore. However, Harry, while on his way to inform Dumbledore of the events, unwittingly alerts Crouch Jr in the disguise of Mad-Eye Moody to his father's presence. Crouch Jr instantly goes to the Forest, proceeds to kill his own father, transfigures his body into a bone, and buries it on the Hogwarts grounds.