Items of clothing belonging to a former passenger representative who was allegedly at the captain's side when the Costa Concordia hit a rock off the island of Giglio last month have been found in his cabin, according to Italian news agency reports.

Domnica Cemortan, 25, from Chisinau, Moldova, has become a central figure in the investigation, which is trying to establish why the captain, Francesco Schettino, took the 114,500-tonne cruise liner so close to the jagged shoreline. Up to 32 people died after the ship listed first one way and then another before capsizing on a rocky ledge further up the coast.

Schettino, who is under house arrest, is being formally investigated on suspicion of multiple manslaughter, causing a shipwreck and abandoning a vessel under his command.

His conduct has been vehemently defended by Cemortan, who told a Romanian reporter that, by bringing the liner into shore after the accident, he saved thousands of lives. Cemortan, a former dancer, also appeared to contradict statements by members of the crew that she had been invited on to the bridge by Schettino on the night of 13 January to watch him execute a sail-past in honour of a retired liner captain. She has denied being his lover.

But after being questioned at length on Wednesday it was reported that Cemortan had admitted she was in love with the Schettino and that she had been on the bridge when the manoeuvre failed. According to one report, rescue workers searching the stricken vessel found her dresses, underwear, cosmetics and other effects in his cabin.

Cemortan first entered the tangled story of the wrecking of the Costa Concordia when a retired Italian couple told their local newspaper they had watched from a nearby table as the captain entertained a young woman at dinner. They claimed Schettino had drunk copious amounts of wine before heading back to the bridge. The captain and his employers have said he is teetotal.

Cemortan's contract with Costa Cruises, the operators of the liner, had just ended but she bought a ticket to spend a week on board the ship as a tourist. A source close to the investigation said at an early stage that she appeared not to have been assigned a cabin.