Last Night's Viewing: Catching a Killer - Crocodile Tears, Channel 4 Dara O Briain's Science Club, BBC2

In retrospect, of the many macabre vignettes that arose from the Philpott case, perhaps the very strangest was one that took place by appointment with the media. Mick Philpott, leaning against his wife Mairead, a tissue clutched to his eyes, his shoulders shaking, his face cast down: a plausible simulacrum of a man weighed down by grief.

And yet, throughout his press conference, Mick Philpott shed no tears. He made no appeal for the killer to come forward. He gurned in weird, alarming explosions of anguish between passages of calm. Darshna Soni, who was covering the story for Channel 4 News, remembered it on Catching a Killer – Crocodile Tears last night. "As soon as he left the room for a few seconds, we were all just completely stunned," she said. "We were all thinking: what on earth have we just witnessed?"

You can see why the topic appealed to the documentary's producers. There's something grimly fascinating about watching such displays in retrospect: the rare chance to see a liar at work in full, confident knowledge of his artifice, and the detective game of looking out for hints at the deceit. Whether there's enough in that voyeuristic interest to support an hour-long film is, on this evidence, less clear.

The idea was to use the examples of the Philpott case alongside the murders of Tia Sharp and Shafilea Ahmed to expose what was termed a "change in tactics": a new media-savvy, brand-conscious breed of murderer with a PR strategy to match their plans for the courtroom. With Philpott, that case is easy to make. The endlessly aired clips from Ann Widdecombe's documentary about his household, his surreal appearance on The Jeremy Kyle Show, and the fact that the whole point of his vile, idiotic arson was to cast himself as a hero all contribute to the argument that it makes much more sense to view this man as a product of "Celebrity" than "Welfare" Britain.

The problems came in the other two stories. Even as the voiceover insisted that Stuart Hazell's murder of Tia Sharp aligned with Philpott's case, we watched a man not pursue the limelight but become visibly unsettled whenever he was forced to stand in it. And while there is something undoubtedly disturbing about the footage of Iftikhar Ahmed and his wife, Farzana, hijacking a police press conference to insist that they did not kill their daughter, it must be remembered that – even though the case only concluded this year – those events took place in 2007. Such evidence doesn't really seem to support the case that this is a phenomenon on the rise.

Had the film spent more time talking to experts about the background and rationale for such PR stunts – probing in a bit more detail, for example, the role that lawyers and the police themselves play in the decision to go public – it might have felt more justified. As it was, the rehashed details of these horrible crimes seemed a little off the point. Such manipulative criminal behaviour is transfixing, to be sure. But by the end I was still unconvinced that these people were really so different from the more ordinary sort of killer.

More cheerful fare was on offer on BBC2, where Dara O Briain and an intrepid team of eggheads returned for a second series of his Science Club. With a set heavily inspired by Top Gear and the same jovial presenter who hosts Mock the Week, the agenda here is as clear as it was last time around, and there were moments when the earnestly intended, Christian-rock-style fusion of hilarity and science felt horribly strained. But O Briain is a winning host, smart enough to ask the right questions and normal enough to let the experts answer them, and he had one crucial factor in his favour: the science, all about the way the mind can be controlled, was incredibly interesting. You can't imagine Clarkson pulling it off.

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