A judge in Argentina has suspended a wedding between a woman and the man convicted of murdering her identical twin sister two years ago.
A final decision on whether they will be allowed to marry is expected by the end of the month.
The twins' mother went to court to block the wedding, saying her daughter is psychologically ill.
Edith Casas, 22, insists Victor Cingolani did not murder her sister Johana, a model with whom he also had a relationship. He is serving 13 years in prison for her murder in 2010.
The mother's lawyer, Fabian Farias, said Edith was "not in full control of her mental faculties". He told told Clarin newspaper that her physical and psychological wellbeing were in danger.
Relatives says Edith had changed in the last 10 days, leaving home to live with Cingolani's sister and announcing the wedding.
The couple had planned to wed on Friday at the prison in the southern province of Santa Cruz, to avoid media attention.
But the judge suspended the wedding, adding that he would make a final decision by 31 December on whether Cingolani and Edith can marry.
The BBC reports the exact circumstances of the killing of Johana Casas, 19, in July 2010, remain a mystery. Her body was found with two bullet wounds in a field.
A second man, Marco Diaz, who was Johana's boyfriend at the time, is awaiting trial charged with her murder.