D.C. prosecutors have stopped sending DNA evidence to the city’s new state-of-the-art crime lab after they said they discovered errors in the way analysts determined whether a sample can be linked to a suspect or a victim, reports the Washington Post.

Prosecutors have hired two outside DNA experts to review 116 cases, including rapes and homicides, and have been notifying defense attorneys.

In one federal case, prosecutors said, the D.C. lab concluded that a defendant’s DNA could have been on the magazine of a gun seized as evidence. But an expert who reviewed the data said the lab should have interpreted the results to mean that the defendant was not the source of the DNA.

In other cases, prosecutors said, the lab either understated or overestimated the likelihood that a particular person’s DNA was left at a crime scene.

Officials at the Department of Forensic Sciences, which is located in a $220 million facility that opened in 2012, defend their work and say disagreements among scientists in the field are not uncommon. The dispute has essentially created a standoff between the city-run lab and federal prosecutors in the nation’s capital.