Four suspects pleaded not guilty Wednesday to charges in connection with the murder of a man who died after he and a woman were found bound and gagged on a street in San Francisco's Visitacion Valley on Sunday.

Montrail Brackens, 21, Vincent Bell, 31, Heather Leach, 24, and Maryann Manalastas, 22, all were arraigned Wednesday afternoon in connection with the death of Stephen Reid, 26, who was found tied up in the middle of the roadway in the 900 block of Brussels Street at about 8:30 p.m. Sunday.

Brackens, Bell and Leach were charged with murder while Manalastas, 22, and Tyler Miller, 19, were charged with conspiracy and being an accessory to the crime after the fact. Manalastas also faces an assault charge, Assistant District Attorney Harry Dorfman said during today's arraignment.

Miller has posted bail and was not required to appear in court. She is set to be arraigned on Friday morning, prosecutors said.

A sixth person, Maelene Lintz, 32, had initially been arrested on suspicion of murder but her case has been discharged pending further investigation, district attorney's office spokesman Alex Bastian said.

According to a criminal complaint signed Wedneday by police, Brackens and Bell entered a home at 3733 San Bruno Ave. and assaulted Reid and a woman in her late teens, then bound and gagged them -- stuffing a sock in the woman's mouth -- and put them in a GMC Yukon.

Leach, whose aliases include Krystal Gillespie and "Snow," was also in the Yukon. At some point, someone shot Reid in the neck and the suspects then dumped the pair on the roadway on Brussels Street, according to the complaint.

A motorist came upon Reid and the woman, who were taken to San Francisco General Hospital, where Reid later died. The woman's injuries were initially considered life-threatening but she is now expected to survive, police said Wednesday.

According to the complaint, the next day, the suspects were at a home on Pinnacle Court in Hercules where they destroyed evidence in the Yukon by spraying cleaning fluid and removing a blood-stained carpet and foam padding from the vehicle.

Bell, whose aliases include Jonathan Stewart and Vince Miller, was also charged with possession of a firearm by a felon. He has previous convictions including one for second-degree robbery in Alameda County in 2001, according to the complaint.

Bell's attorney, Deputy Public Defender Stephen Olmo, said outside of court that his client "is adamant that he did not commit this crime."

Olmo said Bell is "a family man" who is married with three children.

Dorfman, the prosecutor, indicated in court that additional charges, including a murder count, may be filed against Manalastas, who also goes by the alias "Pocahontas."

However, her attorney, Daniel Byrne, said, "There is nothing in here that would indicate anything close to that."

District Attorney George Gascon held a news conference following the arraignment but he and other investigators are remaining tight-lipped about a possible motive in the case.

"At this point we're not clear," Gascon said, although he noted "this was not a random act" because the victims and suspects all knew each other.

"The story here is very complicated," he said. "There's a lot of moving parts."

Bell, Brackens and Leach remain in custody on $2 million bail while Manalastas is being held on $500,000 bail.