LOS ANGELES—Two men charged with murder in the killing of former “General Hospital” actor Johnny Wactor pleaded not guilty Thursday in a Los Angeles court.

Robert Barceleau and Sergio Estrada, both 18, entered the pleas through attorneys to charges of murder, grand theft, and attempted robbery.

A third defendant, Frank Olano, 22, charged with being an accessory after the fact, also pleaded not guilty. A fourth, Leonel Gutierrez, charged with grand theft and attempted robbery but not with killing Wactor, is expected to enter a plea next month.

Emails sent to the LA County Public Defender’s Office seeking comment from the men’s attorneys were not immediately returned.

Wactor was shot and killed when he interrupted three thieves stealing the catalytic converter from his car on May 25. Police and prosecutors said the 37-year-old had left work at a downtown LA rooftop bar with a coworker when he saw three men who had hoisted his car. One of them fired at him without provocation and killed him, authorities said.

After a long investigation that included police requests for help from the public, the four men were arrested on Aug. 15 and charged on Aug. 19.

Barceleau’s charges include special circumstances, including murder during an attempted robbery and personal use of a firearm, that after a conviction could lead to a life sentence without possibility of parole. Estrada’s charges have a maximum sentence of life in prison.

By Andrew Dalton