I'll try to make this as brief as possible and just stick to the facts. Around late February/ early March 2016 my father began behaving strangely. He called me one night to tell me he wanted me to quit my job and come work for him (he did not own his own business, he was a systems administrator for a large company). I was confused and asked him what he meant. He said he wanted to start his own business selling sports collectibles, detailing cars, painting houses, working on computers and basically doing anything anyone would hire him for. I asked him why he wanted to do all of that, and if he was still working at his job. He told me that he was but that was going to change soon because he wanted to work for himself, and he wanted me to work for him too. He also offered me $5,000 to quit smoking. My parents have always hated the fact that I smoke and have asked me to quit numerous times, but my father was never one to "bribe" anyone to do the right thing, and he definitely didn't have that kind of money laying around like it was pocket change. I told my dad that he didn't have to pay me to quit smoking, that I would never take his money like that and that one day when I'm ready I will quit smoking for my health. I kept asking my father if he was okay, he seemed overly excited and more enthusiastic than he normally did, and the things he was saying were just bizarre. He said he was fine, I talked to my mom for awhile and she said he was fine too, just "worked up" about his idea of working for himself. My dad was 65, almost retirement age, and he had worked for the same company for 20 years. He had previously talked about how much he couldn't wait to retire and enjoy the rest of his years relaxing. My dad was rarely sick, never missed a day of work, he normally didn't even get headaches. A few weeks after the odd phone conversation my mom called me and told me that he had tried to kill himself, but a friend had found him before he was successful, and that he was now in a mental hospital a few hours away. He had been there for a day or so already, she said she hadn't told me sooner because she didn't want me to worry about it and that my dad didn't want me to know either. I was in total shock. When my mom and I visited him at the mental hospital he seemed like a completely different person, he was laughing and joking about things in such a fervent way it was alarming, he introduced me to other patients as his wife, and put his arm around me and almost grabbed my ass ( my father never, ever touched me or abused me sexually or physically, I could tell he was so confused he really just thought I was my mom.) Once we sat down together he started telling us this story about how years ago at work his female boss had sexually harassed him and instead of filing charges, he had chosen to work under someone else. Recently that had changed and he had to work for her again and she didn't like him because of what had previously happened and that she had made trouble for him and he was going to lose his job. However, he had a sheet from his company that basically said he had to have a mental health evaluation completed to return to his job. I asked him why his company gave him that and he said it was because he and the security guards had played a practical joke and someone blew it out of proportion. None of that made sense. My head was swimming, my father is one of the most level headed, intelligent people I've ever known and the way he was behaving and the things he was saying weren't like him at all. I went to the nurses station to ask what medicine they were giving him and they told me he wasn't taking anything, the way he was talking and acting was just how he had been since he got there. He was in the mental hospital for about a week or two then he was released. They prescribed him an antidepressant but never diagnosed what was wrong with him. My dad wasn't allowed to return to work yet, my mother had always been a housewife (and she obviously needed to be home to look after my dad) so I took a second job to help support them. They didn't ask me to and even told me they didn't want me to, but all I could think about was the long term care costs of whatever mental disorder my father had, I didn't want him to worry about anything, I just wanted him to get better. Admittedly it was also easier for me to go to work then to sit there and watch him suffer without being able to help. I offered to go for walks, take him anywhere he wanted to go, play checkers, just talk to him or listen, but it was like he lost interest in everything. He didn't want to leave the house, it was like he was afraid to, he kept saying he felt like a burden. I told him over and over that he wasn't a burden and never could be, that I loved him and that I just wanted him to get better. He went to therapy and took his antidepressants and eventually seemed to be more stable and would leave the house occasionally but he was never the same. Once he completed therapy his doctor signed off on his mental health evaluation. At that point he was expecting to return to work but they said they still had some concerns. They kept putting him off each time he would call but finally they met with him. They told him he could either resign and have a severance package, keep his insurance for 6 months and they would hire a headhunter to find him another job in the same field, or they could just let him go and he would have nothing (we live in an at will employment state.) He took the first option with the severance package for obvious reasons but his spirit seemed broken. This was towards the end of June. He started becoming less like himself again, afraid to leave the house, he started saying he wanted to die, trying to choke himself with his own shirt, etc. We took him to his primary doctor and we all talked, his doctor wanted to run some tests and scans so we made an appointment for the following week, the soonest they were able to get him in. The next day I was at work and my mom called me saying she needed help with dad, I could hear him in the background telling her to call the police and tell them he had a gun so they would come and shoot him. I went over there immediately and drove him to the ER. My mom had to sit in the backseat with him to keep him from jumping out of the car. When we got to the hospital he tried to reach for a security guards gun, fortunately they didn't shoot him or hurt him due to his mental state. The next day he was transferred to a mental hospital. They told my mom before they even talked to him, before he even walked in the building, that he would be out in one week. He was released one week later and he killed himself the very next day. That was July 28th, 2016. Almost a year and a half later I am still asking myself what happened to my father. Mental illness runs in his family. His mother was schizophrenic, she killed herself. My cousin died of a drug overdose (no one knows if it was accidental or on purpose) and my uncle (my dad's brother) killed himself after that. My dad had a really hard life growing up, his father was an abusive alcoholic and his mom was mentally ill and suicidal, but he rose up out of that and went to college and married my mom and raised a family. He was the strongest man I have ever known and my hero; nothing will ever change that. I just want to know why he died. Was it possible he was schizophrenic and none of us knew? He never behaved strangely before this. I know him losing his job made him feel like a burden, but since the company he worked for ordered him to have a mental health evaluation prior to that happening, it makes me think that he was already behaving in an unusual manner. I'm lost without him, I feel like I failed him. I feel like maybe if I had just quit working and moved in with my parents and watched him maybe he would still be here. Knowing why he died won't bring him back, but I would still like to know. I appreciate any help.

TL;DR: My father killed himself after appearing "normal" his entire life and I want to know why.