A serial killer with a prior record of theft, fraud, and sexual assault, Beck murdered three women in northwestern Germany between 1961 and 1968, with each case presenting investigators significant obstacles — one victim's father died under a cloud of false suspicion before Beck was ever identified. His 1968 trial became a landmark in German legal history not for its verdict but for the court's agreement to subject him to a chromosome test, the first such application in a German murder case, tied to contested theories linking XYY chromosome patterns to violent behavior. The test ultimately produced no mitigating findings, and Beck died in 2018 having served five decades of three concurrent life sentences.

Working as an attendant at a New York City nursing home, he exploited a position of trust to poison eight elderly patients in his care — a pattern of harm that depended entirely on the vulnerability of those who could not protect themselves. What distinguished his case historically was his eventual confession, made voluntarily and in striking detail, offering investigators a rare direct account of his methods and reasoning. He was committed to an institution for the criminally insane rather than prosecuted, and subsequently disappeared from the record.

His significance lies less in any single act than in the doctrine he left behind — the Revolutionary Catechism, a text arguing that a revolutionary must subordinate all morality, loyalty, and human feeling to the cause. The murder of Ivan Ivanov, a fellow conspirator deemed insufficiently compliant, was carried out as a practical demonstration of those principles. Nechaev's methods repelled even committed radicals of his era, yet his framework for total ideological dedication would echo through revolutionary movements for generations.