When Lord Voldemort first came to power, Crouch headed the Department of Magical Law Enforcment. He became as ruthless as some on the Dark Side, and gave Aurors powers to kill rather than capture dark wizards. He sent Sirius Black to the wizard prison Azkaban without a trial. Crouch appeared to be the favorite to become the next Minister of Magic, when his own son, Barty Crouch Jr, was caught with Death Eaters who were trying to bring Lord Voldemort back to power. Crouch had just enough affection for his own son to give him a trial before sending him to Azkaban. The trial was really a demonstration of how much he hated the boy.
Crouch's 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 and his son drank some that caused him to take on his mother's appearance. In this way Barty Crouch Jr escaped Azkaban and his mother died and was buried, believed to be her son. Barty Crouch held a funeral for his wife, but the casket was empty.
Barty Crouch Jr was nursed back to health by Winky the House Elf. He hid under an invisibilty cloak at all times. Some time later, Bertha Jorkins, Ministry of Magic employee, discovered Crouch Jr. and Barty Crouch put a Memory Charm on her to make her forget what she had seen.
Years later, Lord Voldemort broke through the Memory Charm placed on Bertha Jorkins, and discovered that Barty Crouch Jr. was still alive. Voldemort then decided to rescue him and restore a loyal servant.
Voldemort and his servant Wormtail took control of the Crouch family home and put Barty Crouch under the Imperius Curse. Worried that Crouch would fight the Imperius Curse, Voldemort kept him at his house and had him send owls giving instructions.
Crouch escaped, however, and journeyed to Hogwarts were he met Harry Potter and Viktor Krum and begged to see Dumbledore. However, his son was posing as Prof. Moody and he knocked Krum unconscious as soon as Harry left and killed his father. He transfigured him into a bone and buried it.