Robert Duane Mason was 60 years old when his body was discovered in his home, a modest house in a quiet Encinitas neighborhood where he had lived for 20 years. The homes on Pegaso Street were built in the 1970s, but they were well cared for and showed pride of ownership.

It was his neighbor Jerilyn Heiser who found her friend that Sunday morning, October 16, 2005, lying on his back in his television room. His eyeglasses rested on the love seat, in the crease between the cushions. Blood stained one lens, and the earpiece was bent out of shape. Investigators later said they counted 51 knife wounds on the body.

The middle-aged housewife told investigators that she had last spoken with Mason by telephone the night before at 8:30. They had made plans to go shopping the next morning. So when Mason did not answer his door at 10:00 a.m., Heiser let herself in with her own key.

Just a few days before, the previous Tuesday, Mason had been visiting in Heiser’s house, a few doors down the street. Investigators learned that Heiser and Mason had an unexpected visitor that day. A young man named Brandon Taylor Lee arrived. Lee spoke insistently to Mason, the distraught woman told deputies, demanding access to Mason’s computer.

“She didn’t know why, but he was very insistent that he get on the computer, so they left the house at that time. Mr. Lee and Mr. Mason left the house,” sheriff’s detective Ritchey Hann testified in court almost a year later.

The next night, about 3:00 a.m., a police officer in Carlsbad saw something unusual while on patrol. Officer Brendan Kidd said he spotted a person in a sleeping bag under a piece of construction equipment near the Carlsbad library. The officer approached the man. Brandon Taylor Lee was cooperative, the officer noted. Lee readily provided his name and birth date. The young man wore a light-colored, zippered, hooded sweatshirt and was dirty and unshaven. Kidd concluded that the 23-year-old man was a transient and noted this in his report dated October 13, 2005.

The morning of October 16, officers asked Heiser how it was that she and Mason and Brandon Taylor Lee all came to know each other.

“She stated that Mr. Mason had been an acquaintance of hers for some time and a good friend for a number of years,” Detective Hann said, “and that he was introduced to Mr. Lee through her because Brandon Lee knew her son, Justin Heiser, and had actually lived at their home for a while. At some point, Mr. Lee had nowhere to go, so Mr. Mason agreed to allow him to live at his home as a renter.”

Heiser told officers that her son and Lee had attended the same high school. When Lee was 17 years old, he was reportedly not getting along with his mother, so Lee moved in with the Heiser family.

In 1997, the marriage of Brandon Taylor Lee’s mother and stepfather was dissolved. Brandon would have been 16 years old. In court papers, the stepfather described his former wife: “She rarely spends any time with the children. The boys are in school during the day and I am advised that she is generally out of the home during the evenings and sleeps elsewhere at night, leaving the boys home alone.” At that time, Brandon’s home was in a fancy area of Encinitas, near an equestrian park, where the houses were larger and newer than the houses on Pegaso Street.

So Brandon Taylor Lee moved into the Heisers’ home. This apparently worked well enough for some years, but when Lee was 19 or 20, the Heiser family told him that a niece attending a local college now needed that bedroom. By then, Heiser said, Lee was working and had his own car-detailing business.

So Lee rented a room from Mason.

At some point, Lee moved out of Mason’s home. According to neighbors, that happened around February 2005 — eight months before the older man was found dead. Neighbors said that in the following months they occasionally spotted Lee returning to Mason’s home.

Then Mason was found near the bloodstains on the couch and love seat. Investigators quickly decided on a suspect.

Sheriff’s detective Conrad Berlinsky was sent to hunt down Lee, after asking neighbors where Lee had been seen lately.

Meanwhile, with a search warrant, officers gathered evidence in Mason’s blood-spotted home. In the downstairs bathroom, they photographed an opened box of gauze pads and a gauze-pad wrapper discarded in the trash can.

In the laundry room, a light gray, hooded sweatshirt was found wet in the washing machine.

About four o’clock in the afternoon, Detective Berlinsky spotted his suspect: Brandon Taylor Lee was about a mile from Mason’s house, outside a Starbucks on El Camino Real.

When the detective approached, he noted that the youth was wearing a brand-new pair of boots and that Lee was very clean, considering that it had been raining. Detective Berlinsky thought it odd that someone characterized as a transient would look so clean. He also noted that Lee was carrying a sleeping bag.

Lee was “extremely cooperative,” according to the detective. Lee readily identified himself to the detective and agreed to go with officers to the sheriff’s station to be interviewed. He allowed himself to be searched before getting into the back of the patrol car. He had no weapon and no key, it was noted.

Officers noticed that Lee had a freshly bandaged right hand. It was wrapped with gauze. It turned out that Lee had a fresh cut on his hand.

Lee told investigators that he was 19 years old when he met Mason, who was in his 50s then. Lee confirmed that he moved into Mason’s home and paid rent for a room.

Lee told investigators he definitely was not interested in a sexual relationship with Mason, according to papers filed by prosecutors. Mason had reportedly told friends that he believed Lee was denying his sexuality, according to statements filed by attorneys.

Defense attorneys alleged that Mason put a video camera in Lee’s rented room and that Mason bragged about his relationships.

Lee admitted that he intentionally killed Mason, according to court papers. “The defendant claims that when he killed the victim he was acting in lawful self defense,” one prosecuting attorney stated in papers filed with the court.

But prosecutors say it was murder when Lee stabbed the older man and inflicted those 51 knife wounds.

Dr. Steven Campman, who performed the autopsy, listed the cause of death as multiple sharp-force injuries. The doctor believed the weapon to be a knife about an inch wide, and he said he found defensive wounds on Mason’s hands and forearms.

The majority of wounds were on the face, neck, and chest. There were a large number of wounds in the neck area, made front to back and so closely clustered that the doctor decided the victim was probably not moving much during that part of the attack. Dr. Campman estimated that Mason was killed the evening before he was found, the night of October 15, 2005.

Defense attorneys have stated in court papers that the older man was a sexual predator who sought out young men such as Lee. They allege that Mason offered Lee drugs in exchange for sex acts. Defense proposed that Lee was acting “either in self defense and/or in an uncontrollable rage, due to unwanted sexual advances of the decedent.” These defense positions are found in court papers filed in 2008.

Brandon Taylor Lee is described in sheriff’s records as a white man, 5 foot 8 inches and 150 pounds, with brown hair and green eyes. He will turn 29 at the end of October, and he is now held without bail. He has been in custody since the morning the detective found him on October 16, 2005.

Lee has met many times with mental health experts and has been found mentally competent, and then not, multiple times. During his not-mentally-competent periods, Lee spends time at Patton State Hospital in San Bernardino County.

In July 2006, Lee was mentally competent; then, in June 2007, he was not. In September 2007, he was mentally competent; then, in May 2008, he was not. In August 2009, Lee became competent again.

In September 2009, an attorney stated that Lee had stopped taking his medications, so a judge ordered “involuntarily [sic] administration of antipsychotic medication.”

During one of Lee’s competent spells, in September 2006, prosecutors presented evidence at a preliminary hearing.

The DNA in drops of blood found on the floor in Mason’s home matched Lee’s DNA. A towel found in the laundry room had several blood stains whose DNA matched either Lee’s or Mason’s.

At the end of the 2006 hearing, Lee was ordered to face a single count of first-degree murder.

In January of this year, Lee’s public defender entered a plea of not guilty by reason of insanity. Defense attorney Sloan Ostbye stated in court papers that the defendant “has been diagnosed paranoid schizophrenic and is suffering from hallucinations.”

Next Monday, October 4, at 9:00 a.m., the results of Lee’s latest evaluation for mental competency are scheduled to be presented to the court, in Department 53 of San Diego’s downtown courthouse.