Bristol - (Whodunnit): A 'crazed female nutter' may be the culprit as murder squad detectives dismissed calls today for mass DNA screening of Bristol males.
Joanna Yeates' death circumstances are being compared to the 1974 unsolved murder of 20 year-old student Glenis Carruthers.
Both women were killed in close proximity to one another with neither fatality showing signs of sexual assault.
Some fetishistic similarites are becoming apparent, however, such as strangulation-associated missing footwear.
"It could be a female psycho," a senior investigating officer said today.
"Historically they're much harder to nail because of the degree of sophisticated subterfuge often involved," the police source added.
"And if it's a woman she may strike again very soon - just to prove her dominance over a mostly male-lead police force."
Yeates' murder has triggered a review of up to 20 unsolved local murders, mostly young women of similar age - including Bath hospital worker Melanie Hall, whose 1996 murder remains a mystery.
Next week's planned re-enactment of Jo's last known movements will see a WPC trace her last footsteps around Bristol.
A Crimebotch tv appeal is also planned.