Prison chiefs are planning a clampdown on criminals taking lie detector tests behind bars.
The move comes as a result of the soaring number of inmates asking to sit the controversial polygraph examinations.
Child rapist John McCallum, 53, has asked for a test to avoid taking part in sex offenders’ treatment.
Luke Mitchell, the killer of Jodi Jones, sparked fury by posting a video on the internet which showed him passing a lie detector test 18 months ago.
The move has been welcomed by opposition politicians but criticised by campaigners and victims.
Rachel Steadwood who, along with her twin sister Tracy Brown, was raped by their uncle John McCallum when they were children, said they did not object to him doing a lie test as they knew he would fail.
She said: “It doesn’t make any odds to us if he does a lie test. I know he did it. Tracy knows he did it. We had the best view to know he did it.
“But if he isn’t allowed to take one he will use it to his advantage. It will just give him something else to shout about – to rant and rave about.”
Tory MSP John Lamont, said: “I welcome the fact the Scottish Prison Service (SPS) are planning to clamp down on lie detector tests, a move that is long overdue.
“Allowing criminals convicted by a jury to take a test is insensitive in the extreme. It also makes a complete mockery of the justice system, which is a far more reliable way of determining guilt.”
It’s understood at least seven inmates in Scots jails, including Mitchell, have now taken lie tests.
They include Caroline Igoe, jailed for killing her partner Martin Barclay with a single gunshot to the head in Edinburgh in 2009. Igoe passed a lie test in prison in 2012.
Polygraph evidence is not admissible in Scottish criminal courts but the SPS has revealed it has been asked by ministers to come up with a policy for lie detector tests behind bars.