LYNN - As a busy courtroom swirled around him, Stephen Rizzo stared hard ahead, his gaze and expression grimly fixed. Nearly five years after he found his daughter’s slain body in her bedroom, he would finally see a suspect brought to answer for her death.

But when Joshua Rivera. 27, came before the judge to be arraigned Monday, Rizzo hardly glanced his way. As Rivera pleaded not guilty to first-degree murder charges and was ordered held without bail, Rizzo lowered his sight to the floor. Beside him, other loved ones of Lara Rizzo wiped away tears.

Prosecutors Monday accused Rivera of smothering the 27-year-old in her family’s Lynn home in August 2007, saying fingerprints and DNA evidence linked him to the scene.

The connection only came to light after the state crime lab found a link between DNA recovered from under Rizzo’s fingernails to genetic evidence found almost two years later.

Rivera was charged in 2009 with raping a 15-year-old Saugus girl, but the charges were dismissed when she did not show up for several court appearances, authorities said.

Joshua Rivera is accused of smothering Lara Rizzo in her bedroom.

The state crime lab told investigators of the link last September, and that eventually led to Rivera’s arrest Friday. Authorities said they also determined that four fingerprints found on a plastic bag pulled over her head belonged to Rivera.

“The fingerprints didn’t produce a link until after the incident in Saugus,’’ said Carrie Kimball-Monahan, a spokeswoman for the Essex district attorney’s office.

Prosecutors did not disclose any motives, and Kimball-Monahan said “we don’t know the connection’’ between Rizzo and Rivera. A lawyer for Rivera, Peter Parker, declined to comment as he left the courtroom.

Kelly DeJesus, a longtime friend of Rizzo’s, said she was relieved a suspect was in custody, and stunned that a day she had long waited for was here at last.

“I’m in shock,’’ she said. “I didn’t think it was going to come and it’s finally here.’’

DeJesus said it was difficult to hear the details of how her friend died, but that she was glad to have answers.

She described Rizzo as a loyal, caring friend with a quick wit.

“She had a lot of people who loved her very much,’’ she said.

Another friend, Alexia Gagne, said she hoped Rizzo and her family would receive justice.

“It’s terrible because she was a really good person,’’ she said.

In August 2007, Stephen Rizzo called police to his Lynn home around 8 a.m. after discovering his daughter dead in her bedroom. Police found her underwear around one leg.

Rizzo said he had seen his daughter the night before, but did not know whether she went out or stayed in. He told police that when he discovered her body, the television, lights, and air conditioning were on.

A search of the room found evidence of marijuana, alcohol, and prescription drugs, a police report stated.

Lara Rizzo was found with contusions in her mouth, abrasions on her face, and hemorrhaging on her neck. An autopsy determined that she died after being smothered.

Rizzo’s family declined to speak to the news media on Monday. In a death notice, Rizzo was described as an animal lover and graduate of a local beauty school.

Court records show that Rivera has been accused of domestic assault and destruction of property. Last year, the mother of his son told police that he had beaten her in the past, but she had not reported the assaults “because she was in fear.’’

But Monday, Olga Santamaria said Rivera is a good man and that he could never kill anyone.

“He’s not capable of it,’’ she said. “He’s a loving father. I’m in complete shock. I’ve known him since I was 17.’’

Santamaria said the domestic assault charges were blown out of proportion. She said she was not aware of the rape charges, and did not know if Rivera and Rizzo had a relationship.

Rivera worked at a McDonalds and was about to start work at a Walmart, she said, adding that he was making his child support payments and was regularly visiting his son, Joshua, 5.

“He was doing well,’’ she said through tears. “I can’t believe all this. I didn’t know anything was wrong.’’