GROSSETO, Italy (Reuters) - Prosecutors have concluded their investigation into the shipwreck of the Costa Concordia cruise liner in which 32 people died and are preparing to seek a trial for its captain and seven other people, a magistrate said on Thursday.

Captain Francesco Schettino is accused of manslaughter, causing a shipwreck and abandoning the ship, which was carrying some 4,000 passengers and crew when it hit rocks and capsized after he brought it too close to the island of Giglio.

Francesco Verusio, who headed the investigation in the Tuscan port city of Grosseto, said he expected to file a request for an indictment at the end of January. He said Schettino faces up to 20 years in jail.

A judge will then decide if there is enough evidence to hold a trial.

The 114,500 ton liner hit rocks after Schettino tried to perform a maneuver known as a "salute" - an attempt to show passengers the island and islanders the ship.

He argues he managed to prevent a worse disaster by steering into shallow waters even closer to shore after the impact to facilitate the rescue operation.

Five other members of the crew, including Schetttino's first officer, and three members of a crisis unit set up by Costa to deal with the accident also face indictment and trial.

Costa Cruises is a unit of Miami-based Carnival Corp.

(Reporting by Silvia Ognibene; Writing by Antonella Ciancio; Editing by Sophie Hares)