In fact over the past 20 years I've heard this story at least a dozen times-- where crime "labs" at different levels of government and in different states (eg: state labs, federal lagbs, etc) were caught doing this.
And when it happens, that isn't enough to get people to be able to appeal unless they have evidence the lab did it in their specific case.
One of the problems of our system is that the criminal system is lacks checks and balances. The judges, prosecutors, police all work for the government. They all have the same interests-- they all report to people who want to look "tough on crime".
Since the police immediately take over crime scenes and collect the evidence and then get the evidence analyzed, they have a lot of power to be corrupt in the interest of more convictions-- and the consequences are negligible for being caught.
Whose going to try a dirty cop? You can shoot a guy in the back on video and never get put on trial for it in this country. (I left Texas when a cop gunned down an unarmed black kid who was on his knees crawling away from him... shooting him multiple times in the back... on my college campus. The cop lost his job and then joined the police force in a suburb. No charges were filed. Apparently a black kid crawling away was "threatening" to the white cop. Alas, I moved to a liberal state and was then myself the victim state corruption- though fortunately, the damage was only $3k to a lawyer.)
This is why I think any evidence submitted in court needs to come from an independant lab, done in a double blind way, and with several audit cases sent to that lab regularly (eg: taking dna from people not involved in crimes and send it in as if it was part of an investigation and see if they are fabricating evidence.)
The idea that the government is independant and objective is to me, now that I'm older and have seen these scandals over the years, laughable.
Every time it happens everyone acts like its' a rare thing.
It's not.