Sanchez remains on the run.
Police Commissioner Charles H. Ramsey told The Inquirer last week that Dove had been placed on desk duty while Internal Affairs investigated his alleged involvement with the case.
On Thursday, investigators continued to interview police and prosecutors whom Dove is believed to have spoken with, questioning them about what he might have revealed about his relationship with Sanchez or his knowledge of Vera's killing.
Lt. John Stanford, a spokesman for the Police Department, said he could not comment on the investigation.
"This is an ongoing investigation, and we are going to make sure it's done in a thorough manner as always," he said.
Tasha Jamerson, a spokeswoman for the District Attorney's Office, said that as with any case involving Internal Affairs, her department would conduct its own investigation after being presented with the findings of the police probe. Then, prosecutors would decide whether a crime had been committed, she said.
Dove could not be reached for comment Thursday.
Fraternal Order of Police lodge president John McNesby said he had not heard allegations that Dove had tried to help Sanchez leave the area, but said one of his staff members has been dealing with Dove directly throughout the investigation.
"Hopefully, this investigation shows this detective wasn't involved," he said. "If he was, it is what it is, and shame on him."
He had been romantically involved with Sanchez for some time, the sources said.
And Dove has told investigators he is in love with the suspect.
Sanchez - who police say is 5-foot-8, 130 pounds with dyed blond hair, and tattoos on her arms, chest, and right thigh - has been arrested twice for drugs.
Vera, court records show, had twice been arrested on domestic-abuse charges involving Sanchez, including a case that prosecutors were forced to withdraw after Sanchez failed to appear in court in August.
Sanchez's phone records show that she called Dove shortly after Vera was killed Sept. 8, the sources said.
Investigators believe Dove may have left work early to visit the crime scene. They also think he moved Sanchez's car after the killing. The car has yet to be recovered, and Dove has not told investigators where it is, the sources said.