"Trial By Blood" by John Macken is a sequel to "Dirty Little Lies" and you probably need to read that first before tackling this one, as the two are closely related. The first book was a decent read, nothing special, but good enough for me to pluck this one off the shelf at the library.
Reuben Maitland, the main character of this series, is a forensics officer who has created some brand new process called "predictive phenotyping", in which DNA can provide not only an identity, but an identikit as well (i.e. what the person looks like). In the first book, Reuben lost his job at the police for misuse of his skills - he used predictive phenotyping to find out who his wife was having an affair with - and now works for himself as a kind of private eye who specialises in DNA. He doesn't like the fact he now sometimes works with the very criminals he used to put away.
The plot here has Maitland being anonymously informed that a man named Michael Brawn has been imprisoned on false DNA evidence that Maitland himself approved. Or so it would appear. His signature was forged! The Michael Brawn in prison is an alias. What is his real identity? Why is he there? Through contrivances too long-winded and silly to go into here, Maitland is the one sent into prison undercover to get a swab of Brawn's DNA. Huh? They couldn't have just launched an official inquiry? Obviously, being an ex-crime fighter behind bars, Maitland has to look out for himself....
"Trial By Blood" is all over the place. There's a subplot about a serial offender dubbed "The Thames Rapist" that the police are tracking. There's another subplot about a footballer client of Maitland's who winds up killing his wife and himself after obtaining DNA evidence from Maitland proving his wife's infidelity. The former links in somewhat to the main narrative, yet is resolved "off-scene" without much fanfare. The latter is so inconsequential that you wonder why it was even included in the first place. There's also the matter of Reuben's son Joshua, who is suffering from leukemia. However, he's not 100% sure Joshua is his son, as his wife had an affair, after all.
As the book nears the finishing line, it throws in twist after twist, each one a bit more ridiculous and desperate than the last. While everything is tied up at the end, you come to realise that none of the characters' actions or motives made a lick of sense. And there are plot inconsistencies and holes that you could drive trucks through. For example, when Maitland is put into prison "undercover", they don't bother changing his identity! He's put on remand for the (false) attempted murder of his wife. When he's forced to break out of prison (ridiculous in itself), and on the run, all of a sudden he's wanted for the flat-out murder of his wife! Couldn't a moment of research reveal his wife is alive and well and a HIGH-PROFILE LAWYER???
And, as for said wife - who's name is Lucy - could you find a more one-note character? She's portrayed as nothing more than a self-centred rampaging bitch. While you could hardly call the characters here fully-rounded and three-dimensional, her non-stop unpleasantness really grates after a while.
"Trial By Blood"s final sin is padding. Lots of it. About 150 pages could be shaved off this thing. Maitland's journey to prison to get Michael Brawn's DNA - the crux of the story - doesn't occur until well after 100 pages. The book has nice, short chapters that are handy for when you're reading on the bus, but it means an odd 3 pages of Lucy going "wah, wah, wah, my husband's a prick", or an odd 3 pages of Maitland's old boss pondering OVER AND OVER AGAIN whether he should be trusted or not. It contributes little to the narrative other than upping the word count.
So, no, I can't say I'd recommend "Trial By Blood". The idea of a DNA expert working outside the law would make a great television series, where subplots about bitter custody battles, tracking rapists or going undercover would be more acceptable and more entertaining. But in this book, even with so much going on, Macken still struggles to expand it over the length of the novel.