The partner of missing Romanian woman, Dana Leonte, 31, was arrested on Wednesday after a bone, which preliminary DNA checks have revealed belong to a woman, were found near the village of Arenas, where the couple lived with their baby daughter.
The bone has been sent off for urgent forensic test to ascertain if it belonged to the missing woman.
Sergio Ruiz's arrest comes after police stepped up the investigation into Leonte's disappearance in June following the discovery of the bone as well as checking Ruiz's erratic behaviour and signals from his telephone corresponding to the area where the bone was found.
The arrested man is now officially the main suspect in the investigation and police are trying to piece together the story of Dana's disappearance which started on 12 June when the couple reported that the garage of their house in Arenas had been burgled.
Ruiz has insisted since then that Leonte had returned to Romania because of debt problems and threats. However, her brother, Florín Leonte, has maintained that the woman would never leave her baby daughter and that her partner was behind her disappearance. Ruiz's lawyer, Juanjo Moreno, said on Thursday that his client maintains he is innocent and "is very calm".