A judge dismissed the charges Friday, citing improper "illegal" evidence presented to the grand jury.
Caleb Thomas Schwab was decapitated while on the Verruckt on Aug. 7.
The 168-feet tall slide means "insane" in German. Following Caleb's death, the ride was closed indefinitely.
SEE ALSO: 2 more charged in connection to 2016 death of boy at Schlitterbahn Water Park
Schlitterbahn owner Jeff Henry and designer John Schooley were charged with second-degree murder, and operations manager Tyler Miles was charged with involuntary manslaughter in connection with the 10-year-old boy's death.
Schlitterbahn co-owner arrested in Texas over boy's decapitation death
In 2017, the Schwab family reached a settlement of nearly $20 million in settlement payments, according to court documents.