Death of Domino’s pizza delivery man in Hyde Park described during trial of two men in Boston court

When Tunis walked into the Hyde Park house, he saw the blood in the hallway and chicken wings scattered on the floor. In the corner of a back room, he found the delivery man, Richel Nova, lying on his back.

“Hello,” Tunis called out, not daring to get close.

Nova’s eyes were wide open, but he did not answer. His face was blank. His neck was soaked in blood.

Tunis was one of 10 prosecution witnesses to testify Wednesday during the first day of testimony in the trial of Michel St. Jean, 24, and Alexander Gallet, 22, who are accused of fatally stabbing Nova the night of Sept. 1, 2010. Assistant Suffolk District Attorney Jennifer Hickman said the two men hatched a plan with Gallet’s then 17-year-old girlfriend, Yamiley Mathurin, to order food, then rob the delivery man at knifepoint.

Nova was stabbed 16 times. Afterward, Hickman said, the trio took his cash, the Subaru he used for deliveries, and even the pepperoni pizza he had brought that night in an insulated bag.

Mathurin has already pleaded guilty to manslaughter and will be sentenced at the end of the trial. St. Jean and Gallet have pleaded not guilty to first-degree murder. The trial is expected to last about two weeks.

The testimony Wednesday was often graphic. As Nova’s family tried to look away, Hickman displayed several gruesome images of the bloody crime scene and pictures of the victim’s lifeless body on the floor.

Brian Lomond, a city emergency medical technician, testified that when he arrived at the scene, Nova was no longer breathing. Lomond said he was about to place a breathing device in his throat when he saw the deep gash in his neck.

“We decided that attempts to resuscitate would be fruitless,” Lomond said.

The vivid testimony might never have happened if St. Jean had not backed out of a deal with prosecutors to plead guilty and avoid a trial.

On Tuesday morning, as the jury was being picked, Gallet and St. Jean agreed to plead guilty to second-degree murder and armed robbery. Gallet, who has confessed to stabbing Nova, agreed to serve 40 to 45 years, while St. Jean faced 35 to 40 years.

But during a break in court, St. Jean’s family convinced him not to enter that plea, according to a motion filed by his attorney, Eduardo Masferrer.

He changed his mind again that morning, but by then the prosecutors had taken the deal off the table. The about-face doomed Gallet, whose deal was contingent upon St. Jean’s acceptance.

On Wednesday morning, before testimony began, Masferrer asked Judge Linda Giles to sever the trial of the two men, rather than let them be tried together. He said that Gallet, who has overwhelming evidence against him, could testify against St. Jean out of revenge and a desire to see him go down with him.

“Mr. Gallet may stand up and decide . . . ‘I’m so mad at Mr. St. Jean for not taking the deal that I want him to lose,’ ” Masferrer said.

In an eight-page motion, Masferrer argued that the Supreme Judicial Court has ruled that holding separate trials for codefendants is in the interest of justice if a defendant might lie about his codefendant’s actions to save himself.

Giles, however, ruled against the motion on the basis that Gallet has for years contended that St. Jean played an instrumental role in the killing.

If Gallet testifies and “throws St. Jean under the bus,” Giles said, she could declare a mistrial.

When Gallet confessed in 2010, he said that he slit Nova’s throat while St. Jean stabbed him, then fished through the victim’s pockets, the Globe, citing the indictments, reported in November 2010. St. Jean told police in the days following the killing that he watched but did not stab Nova, according to the prosecution’s case at the time.

During his opening statements Wednesday, Masferrer told the 16 impaneled jurors that St. Jean’s fingerprints were not found at the crime scene. He acknowledged that St. Jean went to the house that day, but said there is no evidence tying him to the crime scene.

“It’s a horrible crime,” said Masferrer. “But the person who did this is not Mr. St. Jean.”

Gallet’s lawyer, William White, chose not to make an opening statement.

During cross-examination of police who were at the crime scene, Masferrer suggested to the jury that in their efforts to help Nova, officers and EMTs might have stepped on blood and inadvertently compromised evidence.

Hickman told jurors that forensic and video surveillance evidence as well as witness testimony would prove the defendants’ guilt.

Cameras on Hyde Park Avenue show the defendants getting off at a bus stop near the house. They later show Nova pulling up in his green Subaru to deliver the pizza, chicken wings, and a liter of Sprite that Mathurin ordered.

“You will see Mr. Nova take some of his last steps as he walks to the driveway and toward the back of the house,’’ Hickman said.

Maria Cramer can be reached at mcramer@globe.com. Follow her on Twitter @globemcramer.