I think there may be several solutions to this, one is: P+T > P > P+S > P+T > F+S > F > F+M > M > P+T > F > F+M > M > M+D > P+T > P+D > P > P+T Where P=police

I think there may be several solutions to this, one is: P+T > P > P+S > P+T > F+S > F > F+M > M > P+T > F > F+M > M > M+D > P+T > P+D > P > P+T Where P=policeman T=thief S=son F=father M=mother D=daughter. It helped me to approach this as some kind of machine, or a universe with weird physics - from there you can establish some basic operations which are then easy to combine into the whole solution.