As investigators await results of ballistics tests to link a Stockton man's revolver to the bullet that killed a Santa Rosa masseuse, they continued to search for other connections between the woman and her killer.

The day after Carole Marie Brooks, 61, was shot to death, suspect John Quincy Ellis, 46, committed suicide by running into interstate traffic Monday as Stockton police officers tried to apprehend him.

A man with "negligible" criminal history, Ellis left behind a trove of questions about why he shot Brooks and whether what appeared to be a botched robbery was his first assault at a massage parlor, Santa Rosa Police Sgt. Steve Fraga said.

"We are actively in the process of sharing information we've learned with this investigation with other jurisdictions to see if they have any unsolved crimes with the same M.O.," Fraga said.

At about 1:45 p.m. Sunday, Ellis sent a text message to Brooks at her small massage parlor telling her he was on his way, Fraga said. Three minutes later the first 911 caller reported hearing yelling and gunfire at the rented unit, Fraga said.

In some of the last words Brooks uttered before she died, she told an officer that a man named John Paul had scheduled a massage but when he arrived demanded cash and shot her when she refused, Fraga said. She also told the officer the man called and text messaged from a 415 area code number that could be found in her phone.

Neighbors told police they had seen the man in the area before, but with a different car, Fraga said.

Two witnesses gave police the last three numbers of a license plate and Det. Brian Reynolds whittled a list of hundreds of possible matches to a rented Nissan Versa. After dozens of phone calls to Hertz rental car agencies, Reynolds convinced an Oklahoma agent to give him the name of the man who rented a car, Fraga said.

Reynolds acquired Ellis' photo from the DMV and tracked him to a Stockton residence, police said. The phone used to text Brooks was registered to the same Stockton address, Fraga said.

Detectives early Monday watched Ellis leave in the Nissan, ostensibly to return the 24-hour rental to Hertz, Fraga said.

Stockton police officers followed Ellis and pulled him over at about 8:20 a.m. Monday for a traffic violation on the March Lane off-ramp of Interstate 5, Fraga said. Ellis yelled at police to shoot him and then ran into the path of an oncoming semi, crouching down before he was struck, police said.

The San Joaquin County District Attorney's office is investigating Ellis' death because it occurred during law enforcement intervention, Fraga said.

Santa Rosa detectives found a .357-caliber revolver at the home Ellis shared with his ex-wife and their two children, Fraga said. The medical examiner found what appeared to be a matching bullet during Monday's autopsy, he said.

Detectives were searching for Brooks co-tenant at the business, someone known only as "Wendy," Fraga said.

"We still have to solve our murder. The fact that he decided to commit suicide in traffic doesn't absolve us of that duty," Fraga said.