From this L'Express article (translation mine):
TITRE: Tuerie à Orlando: Omar Mateen, un tueur "instable et bipolaire"?TITLE: Mass killing in Orlando: Omar Mateen, an "unstable and bipolar" killer?
Décrit par ses proches comme impulsif et instable, l'auteur présumé de la fusillade dans un club gay d'Orlando travaillait pour une entreprise de sécurité. Il avait fait l'objet d'enquêtes du FBI.
Un "coup de sang" dirigé contre la communauté homosexuelle. C'est ainsi que le père d'Omar Mateen, 29 ans et auteur présumé de la fusillade d'Orlando qui a fait 49 morts et 53 blessés dimanche, interprète l'acte de son fils...
...il aurait toutefois prêté "allégeance" au groupe Etat islamique dans un appel passé aux secours quelques instants avant le massacre.
Described by those close to him as impulsive and unstable, the alleged perpetrator of the shooting in a gay club in Orlando worked for a security firm. He was the object of FBI investigations.
A "violent rage" directed against the homosexual community.* That was how the father of Omar Mateen, 29 and the alleged author of the Orlando shooting that took 49 lives and wounded 53 on Sunday, interpreted his son's act...
...he [Omar Mateen] pledged "allegiance" to the group Islamic State (IS) in a phone call to emergency services a few moments before the massacre.
SOUS-TITRE: "Il se mettait à me frapper parce que la lessive n'était pas faite"
Né à New York en 1986, le jeune homme déménage par la suite avec sa famille en Floride, où il entreprend des études de droit à l'université d'Etat Indian River. En 2009, il se marie à sa première femme, dont il divorcera en 2011.
Depuis, il s'était remarié et était père d'un enfant. "Au début, c'était quelqu'un de normal qui tenait à sa famille, adorait plaisanter, s'amuser. Mais quelques mois après que nous nous soyons mariés, j'ai vu qu'il était instable, bipolaire et qu'il s'énervait sans raison", a témoigné dimanche son ex-femme, Sitora Yusufiy, lors d'une conférence de presse depuis Boulder dans le Colorado, où elle est désormais installée.
Au Washington Post, elle témoigne: "Il rentrait à la maison et se mettait à me frapper parce que la lessive n'était pas faite, ou des choses de ce genre". Omar Seddique Mateen était musulman pratiquant, a assuré Sitora Yusufiy. Mais elle raconte ne l'avoir jamais entendu faire l'apologie du terrorisme. "Il n'y avait absolument aucun signe" que ses amis soient des radicaux lorsque le couple vivait à Fort Pierce, en Floride, a-t-elle encore précisé.
SUBTITLE: "He started to hit me because the laundry hadn't been done"
Born in New York in 1986, the young man then moved with his family to Florida, where he studied law at Indian River State College. In 2009, he married his first wife; he would divorce her in 2011.
Since that time, Mateen remarried and became a father. "At first, he was somebody normal, who stayed with his family, loved joking, having fun. But several months after we were married, I saw that he was unstable, bipolar, and that he got upset for no reason," his ex-wife, Sitora Yusufiy, testified on Sunday at a press conference in Boulder, Colorado, where she has been placed for the time being.
She told the Washington Post, "He'd come home and start to hit me because the laundry hadn't been done, or things like that." Omar Seddique Mateen was a practicing Muslim, Sitora Yusufiy affirmed. But she says she never once heard him advocating terrorism. "There was absolutely no sign" that his friends were radical when the couple lived in Fort Pierce, Florida, she said.
The article goes on, but I don't have time to translate more. Some salient points:
1. According to his ex-wife, Mateen had wanted to be a police officer, so he trained with police friends and got a license to carry a firearm legally.
2. He worked as a guard at a facility for juvenile delinquents. Since 2007, he had been an employee at security firm G4S, whose motto is "Securing Your World." G4S tweeted its reaction to the massacre (here).
3. Orlando law enforcement said that Mateen had been interrogated several times in 2013 and 2014. The FBI became interested in Mateen after he began telling some of his work colleagues about links to terrorists. After two explicit inquiries, the FBI determined that Mateen's supposed terrorist links were not cause for alarm.
4. According to Mateen's father, the massacre had nothing at all to do with religion. Mateen apparently saw two men kissing and touching each other and was offended, declaring, "Look at that. In front of my son, they do that."
5. Mateen's father has strong political opinions, and he put out a video on Saturday that was pro-Taliban, and that called for the arrest of certain Afghan officials. The father also claimed to be the president of Afghanistan.
The article's headline is a bit misleading in that you might expect to read some expert testimony as to Mateen's mental state, but as you see, there's no expert diagnosis of bipolarity; there's only personal testimony from maybe two sources. Given that this tragedy only just happened, we're obviously just beginning to sift through the rubble. I don't expect we'll get expert psychological commentary until much later, and whatever opinions we do get will necessary be only speculative.
*The expression coup de sang (literally, a "blood[y] blow") refers to a sudden and extreme surge of pounding emotion, usually anger or rage. A rough and somewhat archaic English equivalent might be "apoplexy."