FORT LAUDERDALE, Fla. - After California detectives used a popular online DNA database to track down a suspect in the decades-old Golden State Killer slayings, other police agencies quickly adopted the same technique.

Since that case was cracked last year, at least 50 other killings and rapes have been solved nationwide by using partial DNA matches to find suspects’ relatives, whose identities can lead to arrests. But complaints about invasion of privacy have produced a backlash, leading the Florida-based database known as GEDmatch to change its policies.

The non-profitwebsite’s previous practice was to permit police to use its database only to solve homicides and sexual assaults. But its operators granted a Utah police department an exception to find the assailant who choked unconscious a 71-year-old woman practicing the organ alone in church. The assailant’s DNA profile led detectives to the great-uncle of a 17-year-old boy. The teen’s DNA matched the attacker’s, and he was arrested.

GEDmatch soon updated its policy to establish that law enforcement only gets matches from the DNA profiles of users who have given permission. That closed off more than a million profiles. More than 50,000 users agreed to share their information — a figure that the company says is growing.

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