Updated

An Argentinian woman will reportedly marry the man convicted of murdering her twin sister in a ceremony Friday to be held at the prison where he is serving out his sentence for the crime.

Edith Casas, 22, steadfastly believes in her husband-to-be’s innocence, although her mother has vowed to do everything she can to block her impending jailhouse nuptials.

"We know this will be hard because she is an adult, but we will go to court to try to have her examined by a psychiatrist,” Marcelina Orellana reportedly said of her daughter, who is set to marry Victor Cingolani. “As far as we are concerned, she does not know what she is doing.”

Casas, for her part, described her husband-to-be as, “a guy who would not hurt a fly. He did not kill her…(My mother) cannot say I need a psychiatrist because I am fully aware of what I am doing.”

Cingolani is now serving a 13-year sentence in a prison in Santa Cruz province for killing Johana Casas, a fashion model, in August 2010.

"I loved Johana, but I love Edith," Cingolani said, according to Agence France-Presse. "I have a beautiful bride and I am going to marry her."

Another man, Marcos Diaz, who had also gone out with Johana, is also doing time over the killing.

Johana Cases, was 19 when she died. Her body was found in a field with two bullet. The exact circumstances of her death are still unknown.

Click for more at Agence France Presse