Louis Colombo testified that he tried before leaving the house late Dec. 12, 2010, to calm an argument that had Deborah Flores Narvaez pushing and pointing her finger into the chest of Jason Omar Griffith, and Griffith grabbing Flores' throat with both hands.
When Colombo returned, he saw Flores' body on the floor. Griffith told him that he choked Flores from behind after she complained that her throat was injured and she needed an ambulance.
The call would almost certainly have led to Griffith's second arrest in two months on a domestic violence charge. The first, after an October fight with Flores, had set Griffith into a depressive tailspin that jurors have been told that Flores, who Colombo knew as Debbie, helped nurse him through.
All the while, Griffith, 31, a dancer in the Cirque du Soleil show "Love" who went by the nickname "Blu," juggled efforts to romance another dancer in another Cirque show.
The fatal argument began with Flores' complaint that Griffith didn't spend enough time with her, Colombo said as prosecutor Marc DiGiacomo asked him to tell the jury what Griffith told him about the fatal moments.
Colombo said Griffith told him the fighting escalated after Flores insisted that Griffith call an ambulance, "and as they were walking out of the room he grabbed her from behind ... choking her from behind."
Griffith told Colombo he tried to listen for Flores' heartbeat, but couldn't hear because of the pounding in his own chest. Griffith said he put a plastic shopping bag over Flores' head to see if she was breathing, but she wasn't. The bag was still there when Colombo returned home.
Colombo acknowledged helping Griffith try to dispose of the body in tubs of concrete, and endured intense cross-examination from defense attorney Abel Yanez about receiving blanket immunity from prosecution as an accessory to the slaying.
Several times, Yanez derided the agreement as "the deal of the century."
Colombo, now 35, told detectives in January 2011 where to find Flores' body in the concrete.
He said he and Griffith had first entombed the body in one big tub. But that proved too heavy to move and store, so the two men trucked it in a rental van to a vacant downtown house, broke the cement apart, removed Flores' remains, cut the legs from the torso, and entombed them again in two smaller tubs of concrete.
"Who does the cutting?" DiGiacomo asked about the dismemberment.
"Jason," Colombo said.
"What does he use?"
"A hand saw."
"Did you see?" the prosecutor asked.
"I just turned away," Colombo replied.
Griffith was arrested the day Flores' body was found. He has pleaded not guilty to murder and could face life in prison if convicted.
His attorneys maintain that Flores had a history of stalking and violence against Griffith and previous boyfriends in Maryland and Las Vegas.
They haven't said if Griffith will testify in his defense.
A key piece of evidence could be a video recording that Griffith made while confronting Flores about his car tires being slashed. In it, Flores admits hitting Griffith, entering his house, looking on his computer, pouring egg whites on his car and slashing three tires.
The trial continues Wednesday.