ROCHESTER, NY (WHAM) – The Monroe County Sheriff’s Office has a new clue in the search for Robert and Mary Ross. Deputies said the last ping from their phone is believed to have come from the area of boat launches in a Charlotte marina. Lt. Chris Fay, Commander of the Scuba Team, said each search they conduct is different. It all depends on whether crews have an idea of exactly where to look for a piece of evidence or a drowning victim. He said as the weather changes from day to day; so do the conditions out in the water.Submerged in the murky and cold waters of the Genesee River, a diver searched the water for clues. “The last known location, I believe, was pinged by the phone, was in the area of those boat launches. So really, it’s a process of elimination at this point,” Lt. Fay said. When it comes to search efforts like these, he said it’s all about teamwork.Crews had to work navigating and breaking up big blocks of ice.”What the ice does, is that it causes erroneous readings on some of the sonar, so we put the diver in the water,” he added. The diver wore a full body dry suit and face mask. This, combined with the clothing he wears underneath helps to keep him warm.”The river has almost zero visibility, so most of the searches for divers are by feel,” Lt. Fay said. He said the terrain underwater is uneven, and water depth can reach up to 30 feet in some areas – just two of the challenges crews work around.Sunday’s diver ran into fishing debris, like fishing lines and hooks, as he searched.”If the target area is more vast, we rely on some of our electronic equipment,” he said. Search crews use sonar as a another tool to help them. “What that does is that it gives us a sound image. We can’t necessarily see through the water, so the sound will interpret the image for us. We look for shadows and general geometric shapes,” Lt. Fay added. Although crews have not found any evidence in the river to help in this investigation so far, they will most likely be back out there mid-week when the temperatures warm up.