AN ARGENTINE woman has tied the knot with a man convicted of killing her twin sister.

No one from the family of 22-year-old bride Edith Casas attended the Valentine's Day civil ceremony in the town of Pico Truncado.

Afterwards, a group of around 20 people threw rocks and eggs at groom Victor Cingolani, who is serving a 13-year sentence for killing the sister, a fashion model named Johana, in 2010.

Cingolani was out on a day pass to get married and escorted by prison guards and riot police.

"I want to start a family with Victor because I love him. He is innocent," the bride said before the ceremony.

The wedding had been planned for December but a judge blocked it, pending a psychiatric evaluation of Edith Casas at the request of her mother.

But Judge Marcelina Orellana ultimately let the nuptials go ahead, ruling there was no evidence that the bride had any psychiatric disorder.

The father was disconsolate.

"For me, they are both dead. Johana is with God and Edith with the devil," said Valentin Casas.