BUDAPEST, Hungary (AP) — Experts have concluded that the captain of a sightseeing boat that collided on the Danube River with a much larger cruise ship was not responsible for the deadly crash that killed 28 people, including himself, Hungarian police said Tuesday.

The small Hableany (Mermaid) tour boat collided with the Viking Sigyn river cruise ship on May 29 near the Hungarian Parliament in Budapest. All but two of those killed were South Korean tourists aboard the Mermaid. Seven South Koreans on the boat survived but the remains of one missing female South Korean tourist have not been recovered.

Col. Adrian Pal of the Budapest Police reported the results of the recently-concluded investigation, which contained 11,000 pages of documentation and over 4,200 photos. Authorities have not released the name of the deceased captain of the Mermaid.

Pal also denied media reports that the Ukrainian captain of the Viking Sigyn, identified only as Yuriy C., had been drinking or was not at his post when the collision took place on a rainy spring night shortly after 9 p.m.

"No signs of alcohol or other mind-altering drugs were found" in samples taken from the captain immediately after the incident, Pal said. "(He) was on the bridge at the time of the accident. There are clear sound recordings of this."

Yuriy C. is the only suspect so far in the case and is under pre-trial arrest until Nov. 30 at the latest. He is suspected of endangering water transport resulting in a fatal mass catastrophe and of failing to offer aid at the time of the crash.

Pal said the Viking Sigyn's captain claimed several times in his testimony that that he "simply did not notice" the Mermaid before the collision after sunset near the base of the city's famous Margit Bridge.

Pal also said the river cruise ship's technical equipment was in working order and that the radar which would have warned his crew about the Mermaid's proximity was turned on, although its sound was off. It was not clear why the sound was off.

"The explanation could be that traffic on the Danube is so heavy that (the radar's alarm) would be beeping constantly," said Pal, saying it could have been hard to filter out the truly unsafe condition from other false alarms.

Police are also conducting a separate investigation into the possible responsibility of the captain and the crew of the Viking Idun, a sister ship of the Sigyn, which it was following not far behind when the collision occurred. Pal said police were trying to determine whether those on the Idun also failed to offer aid to victims of the collision.

The Mermaid was raised out of the Danube by a huge floating crane on June 11. Some of the victims' bodies were recovered weeks after the crash more than 100 kilometers (62 miles) downstream.

Prosecutors are reviewing the investigation to decide how to proceed with the case.