At about 1630, 8/23/2013, a pontoon boat was seen adrift in Placid Lake by witness 1 on the south shore who was using a spotting scope.  At about 1700, the boat was checked out by witness 1 and his wife, witness 2, and no one was found on board it or in the water nearby.  officer, was contacted and informed of the situation.  The 1966, white pontoon boat (MT8000BA) was registered to the victim but the owners could not be located in the area.  The boat was boarded, started up, and driven to shore where it was moored at a dock on the south side of the lake for the night in the hopes that the owners would realize it was missing and would then retrieve it.
     At about 1149, 8/24/2013, I was contacted by officer who said that the wife of the victim had located the boat at the dock and disclosed that her husband had taken it out into the lake at about 1530, 8/23/2013, and had not returned by this morning.
     I responded to campsite #1 at the Placid Lake State Park and talked to the wife of the victim outside a large motor home.  She said that her husband told her he was going out on the boat at 1530, 8/23/2013, and that was the last she had seen of him.  She said he had a habit of running the pontoon boat out into the approximate center of the lake, seeing out his tools, and then going down the ladder to work on the boat from the underside.  She was adamant that he never wore any floatation device when he went into the water.
    When the boat was discovered adrift, there were tools neatly laid out on the deck,  the ladder was deployed down, into the water, and a shirt was left topside as well.  the victims wife said that the victim was very fastidious and would not leave tools  lying around after he had used them and was finished with a project; even at home, he always put away his tools after working with them.  She said he always wore a shirt when he was on the deck of the pontoon boat but always took it off when he entered the water to work on the boat or swim.  Since the anchor lone on the boat was too short to use in the deepest part of the lake (95 feet), he never deployed it.  Instead, he would go far out and let the boat drift while he worked on it or just lounged on it.
    At times, the victim talked to his wife about possibly sleeping on the pontoon boat for a night, but he never told her he was actually going to do it.  When he did not return by dark, (2000, 8/23/2013), she assumed he may had decided to do just that and put away the supper she had prepared.  This was apparently why she had not been too concerned until he had not shown up in the morning on 8/24/2013;  when his absence was noted then, she got another boat to assist her in finding her husband''s pontoon boat.
    According to the victims wife, the victim had suffered two heart attacks and had four "stents" emplaced about eight years ago.  Recently, he had complained of not feeling all that well.  He had been suffering from depression for some time, mainly due to the suicide of a son (years ago), and had been prescribed anti-depression medication.
    From what I learned during the initial phase of my investigation, it appeared that the victim may have suffered a medical event while in the water, or some kind of accident, that prevented him from getting back on the pontoon boat.  I did not obtain any information that indicated he may have decided to leave the area without telling his wife or other family members.  Nothing I was able to determine showed that he may have wanted to disappear, leave everyone and everything that he now had, and start over somewhere else.
     Since it appeared that a drowning may have occurred in Placid Lake, I initiated a call-out for Seeley-Swan Search and Rescue (SSSAR).  Once SSSAR personnel arrived, a jet boat (with elemementary sonar) and two wave runners were used the rest of the day to search for the victim (without success).
    On 8/25/2013, SSSAR, Missoula Sear...
Seeley Lake