To start the ball rolling...

-> se audiază martorii din lucrări din dosarul X : witnesses to the proceedings in case X / case X trial witnesses are (then) heard / interviewed.

Otherwise, there can be a guardian ad litem, rather than a witness ad litem, but I stand corrected.

Without knowing the civil or criminal / police interview context, I can only assume that lucrări does not have the usual (?) meaning of work or working practic/s/es, but something like 'actuaciones' = proceedings in Spanish.