1) Pile of evidence that someone is guilty.
2) Federal "expert witness" allowed and funded to testify it points to X person
3) Defense is broke
4) If defense not broke, judge finds reason why defense expert witness can't present their full argument
5) Prosecution offers plea deal or a gazillion years in jail
6) Person folds when they realize none of their defense is allowed or will be funded, or goes to trial and gets a gazillion years for daring to go to trial.
If you already have a pile of evidence for a crime and an expert witnesses you can keep piling on it's not much of a stretch to dump it on some random person, as we saw here, quite easy actually.
Even your paid defense attorney might never look at the case files at all. Jared from Subway's lawyer got into hot water because he got Jared to take a plea and it turned out he was factually innocent of one of the many offenses he was charged with, and that fact would have been uncovered quickly had the defense attorney ever looked at the evidence, which he said he had not.
Most plea bargains are done simply based on the charging instruments.
This is effectively a truth, but prosecutors are generally held to high ethical standards, where they are expected to drop cases / not bring cases if the evidence doesn't point specifically to the defendant.
That said, there are occasionally times when prosecutors have been caught hiding / burying / not sharing exculpatory evidence (something the police / prosecution found which would help the defense's case against the prosecution). The only reason to do so would be to sandbag the case against the defendant even when there is a shadow of a doubt in the prosecution's case.
Could the solution be to turn lots of local IT / programmers into potential experts to bend down the cost curve?