Italian prosecutors have placed the captain of the Jolly Nero cargo ship under investigation for alleged manslaughter after his vessel slammed into the dock at Genoa's busy port and toppled the control tower into the harbour, killing at least seven people.
As rescue teams in diving suits searched for two other missing people, officials began piecing together how the 40-ton container ship could have sideswiped the port's control tower when weather and sea conditions were "perfect" on Tuesday night. The focus was on whether human error or a technical malfunction was to blame.
The crash occurred at around 11pm as the Jolly Nero was backing out of Genoa's port accompanied by two tugboats and with a harbour pilot on its bridge. At the same time, a shift change was taking place among employees at the control tower, meaning more people were in the building than usual.
"This event is unbelievable because we had the best weather navigation conditions," said Luigi Merlo, president of Genoa's port authority.
Transport minister Maurizio Lupi told parliament that given the "perfect" weather conditions, possible causes of the crash could include an engine malfunction or problems with the cables between the container ship and the tugs guiding it.
He said investigators - both criminal and from his own ministry - were also looking into possible mistakes with the manoeuvre itself or with the speed in which the ship backed out of its berth and turned around to leave the port.
The Jolly Nero's captain, Roberto Paoloni, and the harbour pilot on board were placed under investigation for alleged manslaughter, Genoa prosecutor Michele di Lecce told reporters. He said other accusations were possible.
Such an investigation is par for the course in Italy.
Mr Lecce said backing out of the port was a frequently used manoeuvre to get away from the dock.
"Now we have to understand if it was done correctly," he told reporters. "If it was done according to the way it was supposed to, or if something wasn't respected or if something didn't work. It could be an issue that concerns behaviour - so a human issue - or a technical problem."