The Hungarian police investigation into a deadly two-boat collision on the Danube River in Budapest last month is likely to be prolonged. 

The Budapest Police Headquarters said in a news conference on Tuesday that they secured two terabytes of data, including radio communications, from the Viking Sigyn, a cruise ship that collided with a smaller boat, the Hableany, carrying 33 South Koreans and two Hungarian crew members on May 29.

Hungarian police said they have also collected five-thousand pieces of photographic evidence related to the incident and that they have questioned some 230 witnesses.

Sixty investigators with at least ten years of experience have been mobilized for the case. Authorities say they have put together the largest probe team ever in Hungarian police history. Engineers, psychiatrists and other specialists are also participating in the investigation.

However, police say it's hard to predict when a conclusion will be reached as all investigative contributions must be properly documented and collated.

Meanwhile, it has been determined that the captain of the Viking Sigyn cruise ship was not under the influence of alcohol or drugs at the time of the Danube collision.