Jurors deciding the fate of James Biddinger knew this much to be true: He and a housemate got into a confrontation over a clogged toilet and, in the end, the housemate was dead.

The questions they had to sort through: Was Biddinger, 27, a coldblooded killer who plunged a stiletto-style knife into his housemate’s back? Or was he defending himself during a fight that broke out inside a Montgomery County townhouse?

Monday afternoon, after about eight hours of deliberations, the jury leaned toward the latter, convicting Biddinger of voluntary manslaughter. Not lost on the jurors was the tragedy of it all: Kevin Mbayo, 22, dead after the most inane of problems.

“How in the world did it ever come to this?” said Juror No. 48, who asked not to be named to protect his privacy.

He and other jurors said there was a lack of physical evidence pointing to premeditated murder. Only two people knew exactly what happened inside the townhouse: Biddinger and Mbayo. Biddinger did not take the witness stand, but jurors reviewed a video recording of him telling detectives he never meant to hurt Mbayo.

James Biddinger (Courtesy of Montgomery County Police)

“It was very, very challenging,” said another juror.

The conviction carries a sentence of up to 10 years. Mbayo’s family wanted more. “This is a crime of murder,” said Edward Musa, an uncle.

The confrontation on the night of May 3, 2011, in Germantown came after a day that started with great promise for Biddinger, a waiter at a local Mexican restaurant, according testimony from his fiancee during early stages of the trial last week.

“James was already awake, and he crawled into bed with me and he asked me to marry him,” Nicole Cooper said. “And I said yes. And we were really excited. So we decided to go out.”

The two had lunch, helped set up Cinco de Mayo decorations at the restaurant where Biddinger worked, and eventually ended up on the patio of the Hard Times Café, playing “Cornhole,” a beanbag toss game, while having drinks with a friend. By 11 p.m., the three had returned to the townhouse and headed upstairs.

The friend, Stephanie Johnson, testified that when she went to use the bathroom, she noticed there was no toilet paper. She told Biddinger, who went downstairs looking for an extra roll. He opened a ground-floor bathroom door and was met by the sight of a clogged toilet and a strong odor. He could not find any toilet paper.

Biddinger went back upstairs and grew upset. The tension had been rising between him and Mbayo, who at the time was lying on the sofa downstairs, as he often did. Mbayo was the son of another tenant and did not pay rent.

Biddinger descended the stairs again, carrying a folding-style stiletto. It was not clear during the trial whether Biddinger grabbed the knife then or if he had it in a pocket all day and it was still there.

Police started receiving 911 calls, including one from a basement resident of the townhouse, Miles Willis, reporting “a very loud domestic disturbance” and people being thrown onto the floor. “I can tell you that one of the residents does have snakes in the bedroom,” he added. “There’s a boa constrictor and a python snake in one of the bedrooms, so it’s a volatile situation, and I’d like to get someone here.”

Within minutes, Biddinger, Johnson and Cooper had left the townhouse. Biddinger spoke to a 911 operator.

“I just got attacked by my roommate,” he said. “I actually approached him for not cleaning his crap out of the toilet and he attacked me. . . . He tried to pull a kitchen knife on me and he got my finger. I ended up getting it away.”

Hours later, by 4:30 a.m., Biddinger found himself in an interrogation room, under questioning by two veteran detectives. Mbayo had died hours earlier in a hospital from a stab wound that went into his lung, something Biddinger did not know and the detectives did not immediately tell him.

Jurors watched a video recording of the interview during the trial. They could see Biddinger telling the detectives about the clogged toilet, how he confronted Mbayo over it and how Mbayo attacked him. Biddinger said that at some point Mbayo appeared to have a kitchen knife in his hand — one that wounded Biddinger.

“I didn’t even see it, honestly,” he said, speaking calmly and confidently in a corner of the small room.

The detectives kept getting more information from him.

“We know something happened, but we’re open to your input,” Detective Greg Jordan said, eventually asking Biddinger how it was that Mbayo came to be stabbed.

“When we were rolling around, bear-hugging, if I still had that knife in my hand or whatever it was, then he might have got stuck with it. I mean I know that. I’m not trying to claim that I had nothing to do with his injury,” Biddinger said. “Because it’s pretty apparent. But was there any intention of me inflicting that kind of pain on him? No.”

The detectives told Biddinger they were going to search the townhouse, which caused him to change his story about the knife. He sighed, then said it was his knife and it had come out of his pocket as the men were wrestling.

“It was a stiletto-style, eBay thing,” Biddinger said. “And as soon as it came out of my pocket, he flipped it open and that’s when I went and grabbed it from him.”

Asked where the knife was, Biddinger said he had tossed it out the window of a vehicle after riding away from the townhouse to a Wal-Mart parking lot.

Biddinger eventually asked about Mbayo.

Jordan cleared his throat.

“He’s passed away. He’s dead,” the detective said.

Biddinger burst out crying, grabbing tissues. “Oh my God!” he said.

By late morning on May 4, Biddinger had been charged with first-degree murder.

In her closing argument, Assistant State’s Attorney Carol Crawford said the noise the basement tenant heard was not a fight between two men. It was Mbayo stumbling around after being stabbed.

She said Biddinger then slipped into the kitchen, cut himself with a different knife and planted it as part of a cover-up that also included trying to control what his friends were telling the police. “He did not act in self-defense,” Crawford said.

But Assistant Public Defender Melanie Creedon emphasized how police found Mbayo’s DNA on the handle of Biddinger’s knife, suggesting the victim had control of the knife at some point. And she said that although the bathroom issue may have led to a confrontation, it hardly turned her client into a crazed killer.

“Ladies and gentlemen, it is ludicrous to suggest that the catalyst — this clogged toilet — was such that Mr. Biddinger was so enraged that he came running down and plunged a knife into Mr. Mbayo’s back,” Creedon said.