Richardson firefighters who came to an office building on the 500 block of E. Arapaho were met with an odd chemical smell, too rancid for a regular fire. The source of the blaze was a nondescript suite with no business name on it, Suite 105.
What they found inside on the evening of November 17, 2015 would lead to a strange and horrific story, one of a long-time fetish pornographer and a young man who apparently snapped under the pressure to perform. That night, 19-year-old Daeveion Mangum, of Fort Worth, bludgeoned 60-year-old Michael Castagne to death with a hammer and then set him on fire.
Mangum's trial started on Tuesday. The state's narrative goes something like this: Mangum was an adult who made a contractual business agreement. He knew what he was getting into, then became enraged during an argument and murdered Castagne.
Mangum killed him with 32 blows to the head, but he's pleading not guilty. His defense is arguing that it was an act of self-defense against sexual assault. They argue that Castagne had for months "groomed" Mangum to get him to perform in a video that included oral sex with and masturbation of another man. When he refused that day, the defense claimed, Castagne tried to force him.
Castagne managed a wine bar, but in his spare time he produced and sold low-budget porn on his website JockPhysical.com. The site specializes in medical fetish films.
Castagne's signature was shooting films in which he was a doctor giving an exam to a male patient, though his head was always cropped out of the frame. His "patients" were always young, usually in their teens or twenties. The "exam" consisted of normal things a doctor might do, but would end in a prostate exam and usually include the patient masturbating and having dildos or other sex toys inserted into his anus. He worked with only of-age men, having kept meticulous records of all of his clients, according to investigators.
The business relationship between Mangum and Castagne began in last April. Mangum had learned of Castagne after seeing a Craigslist ad for modeling with "Nu-Face Modeling," Castagne's cover name for his pornography business, though the space he rented in the industrial park in Richardson was under the name "The Brotherhood LLC."
The application consisted of questions about sexual preferences, along with what would be considered normal questions for a modeling agency. Mangum needed some extra money and applied. He was a young husband and father, with a 2-year-old and a 5-month-old to support.
Mangum interviewed with Castagne, who asked for valid identification to show he was of age. Mangum signed a contract to work with him, which included a clause stating that the client understands he may be subjected to public shame, embarrassment and criminal acts.
After their first meeting, Castagne sent him emails telling him how he'd help him get into "mainstream modeling" and how much he enjoyed seeing his clients succeed. Throughout those months, Mangum participated not only in photo shoots, but in the types of videos that Castagne put on JockPhysical.com.
Mangum participated in at least three of these videos and earned more than $1,100, according to the prosecution. In his interview with Richardson detectives after the murder, he said he never told his wife about his work for Castagne.
Early on in their business relationship, Castagne showed a caring attitude toward Mangum, the prosecution stated. In a series of emails presented in court, Mangum asked Castagne to pay him in advance so he could pay for diapers. Castagne said that he usually never did that, but he would for Mangum. He also often picked up Mangum from his Fort Worth apartment and drove him to the office because he didn't have a car.
"You can count on me because I love this work," Mangum wrote to Castagne in an email. "I won't mess this up for nothin'."
In the weeks leading up to his murder, Castagne was corresponding with another client, 25-year-old Tyler Griffith, who had been working for Castagne since he was 19. He said he wanted to do a "massage therapy" video, where Griffith would be getting massage therapy for a skateboarding accident and another man would be his therapist. There would be mutual "jerking off" and oral sex, Castagne wrote in these emails. Griffith agreed to it.
On November 17, Griffith arrived at the office in Richardson a little early — around 11:15 a.m., he said. A few minutes later Castagne drove up with the other man who he assumed would be doing the video at the office. That man was Mangum.
Mangum claims he was never told that he would have to participate in sex with another man. Mangum was visibly surprised when he saw the other actor, Griffith said on the stand Tuesday.
The three men sat down to talk about the video and Mangum allegedly asked Griffith if he knew this was going on. Griffith told him, if you're uncomfortable, just tell "Mike," which is what Castagne often went by. He'll understand, Griffith assured him.
When Mangum did speak up, however, Castagne was frustrated, Griffith said. After a conversation, everyone seemed to calm down and Castagne agreed to do solo sessions with each of them instead.
After his session last November, Griffith went home to McKinney. Later that night, he saw a picture of Castagne's face on the news. He called Richardson police, telling them he thought he knew who might have killed him.
Mangum's trial is ongoing, with the prosecution to offer up one more witness before the defense presents its evidence. The trial is expected to end Friday.