A woman described as "singularly cold-blooded" went on trial in Austria on Monday accused of murdering two men and setting their sawn-up body parts in concrete in the cellar of her ice cream parlour.

Dubbed the "trial of the year" in Austrian media, Goidsargi Estibaliz Carranza Zabala, who has joint Spanish-Mexican citizenship, is charged with shooting dead her husband in 2008 and in 2010 her new partner.

Prosecutors allege she then sliced up the bodies of her first victim Holger Holz and the second, Manfred Hinterberger, with a chain saw and concealed the pieces in lumps of concrete that she mixed in the cellar under her "Schleckeria" shop in Vienna.

The gruesome remains were discovered by chance during maintenance work in June 2011. After going on the run to Italy, Carranza was captured several days afterwards and later extradited.

When arrested, Carranza was two-months pregnant by another man, whom she married in prison in March this year. The baby was born in January but the boy was immediately taken away from her and is now reportedly being looked after by Carranza's parents in Barcelona.

A psychiatric report commissioned by the court said that Carranza, now in a unit for the "mentally abnormal", was dangerous and was like a "princess ... who just wants to be 'rescued' by a man".

"She intends to confess. She has already told the court-appointed expert everything that she did, as she also did when she was arrested by the Italian police," Werner Tomanek, one of her defence lawyers, told AFP.

Carranza allegedly shot both victims at close range with a .22-calibre Beretta pistol, in Holz's case as he worked on his computer and Hinterberger as he slept. Before the second killing she took shooting lessons as well as a course in mixing concrete at a local hardware store.

Immediately after disposing of Hinterberger, she booked an "urgent manicure appointment" in order to repair her damaged nails, according to the charge sheet.

"This woman has two faces," prosecutor Petra Freh told the packed courtroom on Monday. "She will try to play here the part of someone well-behaved, who would never do something like this.

"My task is to show you her other side ... That she is a singularly cold-blooded and unscrupulous killer," Freh said. "Do not be fooled."

Wearing a grey dress and glasses, Carranza showed no emotion as the accusations against her were read out.

The trial was scheduled to last several days, with around 50 witnesses and seven experts due to testify.

[Image via Agence France-Presse]