Police officers and others in law enforcement and corrections become experts at reading body language. When Alex misses a meeting with his PO, it would be instantly considered suspicious. If Alex is confronted with this at the next opportunity, looks around the room and won't make eye contact with the PO, it might tell us that he is benig deceptive. People are much more likely to make eye contact when telling the truth.
It could also be that he is under the influence of drugs and wants to avoid eye contact so that the PO can't see the pupil dilation or redness and give him a drug test.