Anatomy of a murder investigation

Twenty-three hours into the St. Paul police investigation of the second and third homicides of 2016, Senior Cmdr. Tina McNamara leaned forward in her chair, a silk scarf around her neck, a phone pressed to her ear.

"We booked two for murder today and we're about to book the third," said McNamara, head of the homicide unit, "and he's the baddest of the bad."

The time was 8:37 p.m. on Wednesday, March 23. McNamara and her team of five homicide investigators had been awake for about 40 hours, having worked a regular shift and then reconvening when the bodies of Dominique Charles Moss, 23, and Nicholas Bennett Tousley, 30, were discovered about 9:33 p.m. the previous night.

The investigation unfolded over the course of a day, several cups of coffee and multiple interviews with witnesses who lied, cried and doubled down in hopes of saving their own skin. The process has repeated itself an average of 13 times annually for the dozen members of the unit over the past five years, and eight times so far this year.

Early on, police knew this: A group of men converged at St. Paul's Midway Motel on N. Snelling Avenue, where drugs were allegedly being sold. In minutes, two of them were dead — one collapsing a few feet from Room 15 and the other sprawled on the edge of a nearby off-ramp, where he succumbed to a gunshot wound to the back. But the identities of the men killed — and the people responsible — were unknown.

Investigators caught a break when they recovered surveillance video from a camera pointed at Room 15. Unlike so many others, this camera's footage was clear.

It showed men arriving, shots being fired, men pushing and shoving their way out of the room and the alleged getaway car — a dark-colored Lexus. One of the men involved wore clothing with a distinctive pattern — a long-sleeved shirt with a diagonal black stripe.

Fast, but methodical. Investigators sifted through information from more than 20 witnesses, tracked people down by their nicknames and watched under cover of darkness as suspects sat at home, unaware of the net slowly closing around them.

Witnesses lined a long hallway leading to the homicide office on the second floor of police headquarters shortly after the shooting: two good Samaritans who stopped to perform CPR on Tousley, men possibly connected to Room 15 and motel guests who had the misfortune of renting a room there that night.

Four homicide investigators — Sgt. Tom Arnold, Sgt. Amy Boyer, Sgt. Tim Pinoniemi and Sgt. Eric Skog — sat around a long table in the center of the office, divvying up duties and witnesses. Back at the crime scene, homicide investigator Sgt. Shawn Shanley and others continued documenting and collecting evidence.

"What'd you get?" McNamara asked as Arnold stepped out of a witness interview room.

"Nothin,' " said the white-haired, broad-shouldered Arnold. "Said he heard a gunshot, then heard another gunshot."

"We could go two days without these guys going home — three days," McNamara said about 1 a.m.

Skog sat in a corner listening to 911 calls as he drafted a search warrant affidavit that would later be hand-delivered to a judge's home in the middle of the night to be signed. Boyer interviewed a man who stopped to help Tousley. Afterward, police drove him home.

The investigation seemed to gain traction when Pinoniemi, the lead investigator, began interviewing a man who possibly knew the shooter's identity.

"I'd say we're ahead of the game," McNamara said as she coordinated and oversaw the different parts of the investigation.

A minute after her hopeful declaration — 1:13 a.m. — Pinoniemi left his interview deflated: "He didn't see the shooting."

By 2 a.m., investigators were no closer to the shooter. The answer, they were sure, was in that surveillance video. When Shanley arrived with it, they crowded the table and looked with rapt attention at a TV monitor hanging from the ceiling.

"Two, three, four, five people go in and it starts right away," McNamara said, narrating the video. "Who do we think was in the room to begin with?"

They paused the video on some men walking near the motel room — an image they'd returned to repeatedly. If they could just get to one of them.

Hours from daybreak, several media calls prompted police spokesmen Sgt. Mike Ernster and Steve Linders to hold a 4 a.m. news conference even though much of the case remained a series of half-clues.

Twelve minutes after the press briefing, Shanley announced a key development: "They're sitting on one of our guys." he said.

Benner, 30, sat on the porch; it unnerved McNamara.

"Why's he on the porch when it's cold out?" she asked. "He has to know we're lookin'. Tom, do you think he's alive on the porch? Did he move?"

"I heard he's a terrible alcoholic," Arnold answered. "Maybe he's passed out on the porch."

At 4:51 a.m., police moved in. They were one step closer to the triggerman.

Investigators questioned witnesses one-on-one, leaving small interview rooms to debrief their colleagues, strategize and compare notes, and to give witnesses time alone to think and reconsider.

Soon after he arrived at headquarters, Benner told investigators a man named Nick, the victim found on the off-ramp from Snelling to Pierce Butler Route, had allegedly stolen $1,000 from his friend, Ronald Conway. Benner admitted to driving Conway, 30, and other men in the surveillance video to the Midway Motel so Conway could collect the debt.

Benner was booked at 9:37 a.m. for his role in the crime. Authorities allege in criminal charges that Conway and his associates hid outside and converged on Room 15 after Benner knocked on the door.

Within the hour, Conway was sitting across from Pinoniemi in one of those interview rooms. They had tracked him down through his cellphone's location.

"He keeps saying he wants a deal," Pinoniemi briefed his colleagues an hour into the interview. "He says he didn't have anything to do with it."

Investigators decided to try their luck; they weren't ready to give him any deals. But the news wasn't hopeful when McNamara asked, around noon, if he'd bagged a confession.

During a brief and rare break for lunch, Arnold returned from the medical examiner's office: Each man had been shot once in the back — straight through — and neither bullet was found at the crime scene. Both had been officially identified.

Conway lawyered up soon afterward, ending the police interview, but not before dropping an important clue.

" 'Black' did it," Pinoniemi recalled Conway saying.

"Who's 'Black'?" Arnold asked.

"Dunno," Pinoniemi replied.

"So, he says he doesn't know Black's name, but Black's number is in his phone under Black," Pinoniemi told McNamara about 2:26 p.m.

Cross-referencing information from Facebook and other records, investigators tracked down Black's true identity — 31-year-old Cass Cordell Oneal. Photos from the social media site and the motel's surveillance video showed him wearing the same long-sleeved shirt with a diagonal black stripe.

Officers in unmarked cars watched the apartment of Oneal's sister as his phone was tracked. At 6:22 p.m., the SWAT team left headquarters. Hours of investigative work had led them to a nondescript building in the 1300 block of White Bear Avenue. They were outfitted and prepared for the worst, but the climax was swift, the moment barely perceptible to passersby on the street.

"Number one is in custody," a voice called out over the police radio at 6:32 p.m.

By 7:11 p.m., Oneal was being pressed by Pinoniemi at headquarters. The homicide office hummed with subdued excitement as evidence from the apartment arrived.

McNamara and Pinoniemi high-fived in a rare and brief moment of celebration. The distinctive shirt had been recovered from the apartment, too. It wouldn't take two or three days to catch the alleged killer — just a little under one.

"It's the teamwork," McNamara said. "We work well together. We never gave up."

Breaking a case is all-consuming, and the pressure and work don't stop just because a suspect is behind bars. Arnold awoke at home Friday, March 25, lost in the fog of homicide.

"When I woke up this morning, [my wife] came out with a card and a gift, and I didn't know what it was for," Arnold said. "And I thought, maybe, it was for Easter."

It was for his 21st wedding anniversary.

Chao Xiong • 612-270-4708