“They were like brothers,” Shay McCowan said.

Shay McCowan testified in her brother’s trial Monday morning, crying through most of her testimony. When she began testifying, Connor McCowan became emotional, as well. Phone records obtained by police show that Shay texted Connor McCowan that night, saying Singler had broken her back and one of her ribs, injuries that police said she was never treated for.

Connor McCowan then argued with Singler through a series of text messages and drove to his apartment in Meridian Township to confront him.

Connor McCowan’s dad, Okemos resident Randy McCowan, was asleep on his couch when his son woke him at 4 a.m. on Feb. 23. McCowan also testified Monday.

He said Connor McCowan told him about the altercation and said he feared for his life and retaliated in self-defense. The two called Singler’s cell phone several times, then drove to Singler’s apartment. Upon their return, Connor McCowan was arrested.

Surveillance footage obtained by police from a Speedway gas station, which Connor McCowan stopped at on the way to confront Singler, showed he had changed his clothing before his arrest.

Randy McCowan said he and Connor McCowan had forged a bond with Singler in the two years he dated his daughter.

“I felt like he was a son to me,” Randy McCowan said. “I loved him.”

Throughout their relationship, Shay McCowan said she and Singler argued “fairly often,” with no physical altercations until February 2012, when Singler suddenly became violent during a fight.

“We got into an argument, and it led to some pushing and shoving,” Shay McCowan said. “He pulled a sheet over me and hit me so hard, I had a handprint on my stomach for about three or four days.”

The text messages between Connor McCowan and Singler became heated that night, with an intoxicated Singler telling him to get to the apartment and calling Connor McCowan names such as “queer” and “slut.”

“Hurry up … so I can f***ing kill you,” Singler said in one text message. “Not literally, but your ass needs to get beaten and guess what p**** I’m gonna f***ing make sure it happens.”

John Bechinski, the forensic pathologist at Sparrow Hospital who performed Singler’s autopsy, said Singler had a blood-alcohol level of .124 and traces of THC in his system. He said Singler also had scrapes on his neck, as if someone had grabbed him by the collar of his shirt.

Connor McCowan only had minor injuries, including bruising and swelling above his left eyebrow, which Bechinski said could have been caused by a blow to the face.

By the time Singler arrived at the hospital at about 4 a.m., trauma surgeon Dr. Ben Mosher said he had a 10 percent chance of survival. Singler had a wound in his heart and had lost more than a liter of blood.

“He had no vital signs,” Mosher said. “He was not breathing on his own, he had no pulse, no electrical activity. He was pretty much dead.”

Mosher said Singler’s heart stopped beating during an emergency operation. Singler was pronounced dead at 5:15 a.m.

Connor McCowan’s trial will resume 8:30 a.m. Tuesday. It could go until the week’s end.