Friends and supporters of slain actress and yoga teacher Tricia McCauley held a candlelight vigil for her Dec. 27 in the District. (Michael S. Williamson/The Washington Post)

A Washington-area man on Wednesday admitted guilt in the fatal beating of a well-known local actress and yoga instructor on Christmas Day last year.

Duane Adrian Johnson, 30, was a stranger to Tricia McCauley, and police say he confronted her as she was headed to meet fellow members of the District's theater scene at a holiday party. The 46-year-old McCauley never arrived, and friends began to worry and reported her missing.

McCauley's body was later found in the back seat of her white Scion. She had been brutally beaten and strangled, and her legs had been bound with a seat belt, police said. She also had been sexually assaulted.

On Wednesday in D.C. Superior Court, Johnson pleaded guilty to first-degree felony murder. He faces a 30-year prison term when he is sentenced by Judge Hiram Puig-Lugo on Nov. 17.

Speaking from his home in Oregon, McCauley's father, Henry McCauley Jr., said he thinks a 30-year sentence is "sufficient." He said he chose not to attend the hearing but has been in touch with prosecutors and police and supported the plea deal.

The retired Air Force officer paused briefly as he added the prison sentence to Johnson's age, noting the defendant would be about 60 years old when released.

"He'll be an older man," Henry McCauley said. "We're just not the type of people who want to see vengeance."

It has never been clear how Tricia McCauley encountered Johnson, who, according to his family, suffers from mental illness and was living on the streets. Henry McCauley said it would have been in his daughter's nature to try to help someone like the defendant.

"She was very sympathetic to people who had nothing," he said.

After Johnson was arrested, according to charging documents, he told police that McCauley had offered him a ride. He said he and McCauley had sex and that afterward she committed suicide by hanging herself with a seat belt. He then told detectives that he drove around the city with McCauley's body in the back seat and that he thought she was "sleeping" and would "wake up."

Johnson's guilty plea marks a dramatic shift for the defense. After Johnson's arrest, his attorneys with the District's Public Defender Service had repeatedly argued in court that their client was mentally ill and that police arrested an innocent man who had nothing to do with McCauley's death.

The plea came before Johnson was indicted by a grand jury. "Pre-indictment" plea agreements are often seen favorably by prosecutors and judges. Had Johnson been found guilty at trial, he would have faced more than 60 years in prison. The plea deal is not final until it is approved by the judge at sentencing.

At Wednesday's hearing, Assistant U.S. Attorney David Misler recounted details of the crime. Misler said that once McCauley was inside the car with Johnson, he beat her repeatedly in her face, fracturing her nose. Johnson sexually assaulted McCauley and choked her with the scarf she was wearing, the prosecutor said.

McCauley, Misler told the judge, kicked and punched Johnson but was unable to fight him off. McCauley died of strangulation and blunt-force trauma to her head and body.

When her body was found, her legs were tied together at her calves with the rear seat belt. She was wearing black stockings that were torn above the knees. Her shoes were missing and have not been found.

Johnson's DNA, Misler said, was found on McCauley's body.

During the hearing, Johnson gave brief answers to the judge's questions. He repeatedly turned to look toward the courtroom gallery, but it was not clear why.

Johnson has a long record of arrests, mostly for theft and nonviolent crimes, in the District, Maryland and Virginia. Court files contain notations of possible mental illness, though he has been ruled competent in the past.

The day McCauley went missing, a Sunday, she had prepared a pie and her signature Brussels sprouts to take to the Christmas dinner. When she failed to show, her friends and family launched a search for her, scouring city blocks.

Late the next night, a man walking his dog near Dupont Circle spotted McCauley's white two-door Scion iQ with its "Plant more plants" bumper sticker. He called police.

Police found the car a few minutes later parked in the 2200 block of M Street NW in the West End area. In a nearby CVS store, they confronted Johnson, who had been spotted driving the Scion. A police report says that an officer asked Johnson for the keys and he handed them over. McCauley's credit cards were also found in Johnson's pockets.

Also as part of Johnson's expected sentence, he would have to register as a sex offender for life and be under supervision upon release from prison.

Henry McCauley said he and other relatives had visited his daughter in the District in October, two months before she was killed. His family is doing okay, he said, and Tricia is frequently on their minds.

McCauley said that in her last years, his daughter had all but stopped with theater work, had gone back to school to earn a master's degree and was turning full time to work as a nutritionist.

"We talk freely about her life," he said. "She led a very productive and good life."