This is the 5671st most frequent Russian word.
преступных
"Criminal" or "illegal."
Here, "преступных" is used as an adjective qualifying "действий" to refer to actions that involve crime.
Полиция расследует серию преступных действий.
The police are investigating a series of criminal activities.
In this sentence, "преступных" describes "замыслов" to denote ideas or plans that are against the law.
Она осуждала все формы преступных замыслов.
She condemned all forms of criminal schemes.
Here, "преступных" is used adjectivally with "группировками," referring to groups engaging in illegal activities.