It likely will be a few weeks before investigators can precisely say how two Nevada teenagers died during a scuba diving excursion Saturday off Cannery Row.

Stephen Anderson, 16, and Keegan Aiazzi, 17, were among a group of divers from a Carson City, Nev., high school oceanography class who went into the water from a commercial dive boat about a quarter mile from shore.

After they failed to surface and were reported missing, rescue divers from the Monterey Express charter boat found them on the ocean floor about 70 feet underwater, and they subsequently were pronounced dead at Community Hospital of the Monterey Peninsula.

The divers' deaths, which left the tight-knit Carson City community in shock, is being investigated by the Monterey County coroner's office and the Coast Guard. If foul play was suspected, Monterey police would handle the case.

The apparent cause of the boys' deaths was drowning, but coroner's detective Kim Gardepie said it will be a few weeks before the investigation is complete.

"I'm not going to call it that ... until I've spoken to everybody who was on the scene and have a clearer picture of what went on underwater," Gardepie said Wednesday.

It will take a few weeks for results of toxicology tests on the victims to be finished, he said.

Sheriff's Office spokesman Cmdr. Mike Richards said investigation of scuba diving deaths entails getting expert evaluation of the diving equipment involved.

Air tanks and other equipment

used by the two teenagers remained missing Wednesday as members of the sheriff's dive unit scoured the ocean floor searching for them. Divers looked for the equipment Sunday and Tuesday.

"I need to get those tanks back. That's a big part of the investigation," Gardepie said.

It isn't unusual for tanks and other equipment to be left behind during a scuba diving rescue, Gardepie said.

The investigator expects the equipment to be found, though "a certain amount of drift" and uncertainty about the location of where the tanks were abandoned made for a larger search area, he said.

It is not unprecedented for equipment never to be recovered in scuba-death investigations, he said.

That has happened with diver deaths off Monastery Beach south of Carmel, where fierce currents, a quick drop to deep water and many underwater crevices make it sometimes impossible to recover tanks and other equipment, Gardepie said.

He said the captain of the Monterey Express has been "very forthcoming" and there is no indication of wrongdoing by the charter crew.

The Carson City School District said the boys were on a scuba diving event organized by a scuba business in Reno, Nev., identified by local Nevada media as Adventure Scuba.

A woman who answered the phone Wednesday at Adventure Scuba said she preferred not to comment about the deaths and hung up. The business website says it offers scuba classes and trips.

The Coast Guard certifies and annually inspects commercial dive vessels that carry six or more passengers.

Coast Guard officials made a quick inspection of the Monterey Express after Saturday's search-and-rescue operation and found nothing amiss, said Coast Guard Lt. j.g. Laura Williams.

The Coast Guard's regulation of commercial dive boats is limited to vessel safety features and the crew's ability to properly handle a vessel.

"The diving side (is regulated) by the diving industry and the company the vessel is working for," she said.

Williams said the Coast Guard investigates every marine-related death or injury and will work with county investigators on its probe of the weekend fatalities.

Gardepie said he plans to interview members of the student diving group, the charter boat crew and others involved in Saturday's diving trip. He said he will use the boat's manifest to determine every person who was aboard.

Nineteen divers went into the water, and Gardepie said the group was made up of students and dive instructors. He said he didn't know the ratio of students to instructors.

The 42-foot Monterey Express has operated out of Monterey since 1996, according to its website. The vessel can handle up to 30 divers, but limits groups to 20 divers, the site says.

The first 911 call that divers were in trouble came at 12:25 p.m., and the first report the two stricken divers were recovered came at 1:41 p.m.

Gardepie said he didn't know how long the boys were missing before they were found at a depth of 72 feet.

The boys were recently certified as scuba divers, according to the school district. They made earlier dives in Monterey late Friday and early Saturday.

Source: http://www.montereyherald.com