Mark is a parody of a police officer at the moment. Following Ned round like a stalker because he suspects him of cheating on Elly - someone Mark barely knows. Since when did a member of the public's lovelife become a police matter? The thing I find most irritating is that the writers seem to think we believe Mark to be wonderful and admirable for being such a vigilant superhero. I want to kick him in the nuts on a regular basis right now.
Ironic that Mark's decided Ned's apparent cheating on his new girlfriend is worthy of police interest when he's just been suspended himself for actually breaking the law and bugging a confessional - which has now conveniently been dropped. Mark has such a holier-than-thou attitude towards everyone else, but lies about his own rule-breaking, which is then swept under the carpet by his superiors.
As one of the other posters pointed out on the main Neighbours thread - is it realistic that the only action the local police force would take upon learning a dangerous prisoner had escaped, would be to phone Mark once? Rather than it dawning on them that Ari might go after Steph, and stake out her house, or take her back into protection.
Mark's behaviour is sometimes overlooked because the actor is hot - but I find that pudgy grumpy little boy scowl he permanently wears these days while pursuing his current outrageous obsession, to be highly unattractive.