Two of the 4 men arrested in the slaying of "General Hospital" star Johnny Wactor have been slapped with murder charges. Los Angeles County District Attorney George Gascón announced the charges Monday ..

. while 4 men have been charged with multiple felonies in connection with Wactor's death, only 2 were hit with murder counts. Prosecutors say 18-year-olds Robert Barceleau and Sergio Estrada are both charged with Wactor's murder.

Barceleau's charge includes a special circumstance allegation of murder during an attempted robbery ...

and, as a result, he's facing the possibility of life in prison without parole. He's also charged with one count each of attempted robbery and grand theft, both while armed with a gun. Estrada is also charged with murder, as well as attempted robbery and grand theft, both while armed with a gun .

.. but unlike Barceleau, his murder charge does not include the special circumstance allegation.

Meanwhile, 19-year-old Leonel Gutierrez is charged with attempted robbery and grand theft while armed with a gun. The fourth suspect is 22-year-old Frank Olano ..

. he's been charged with accessory after the fact to murder, receiving stolen property, and 3 counts of being a felon with a firearm. TMZ broke the story .

.. cops swooped in early Thursday and executed multiple arrest and search warrants .

Johnny was shot and killed back in May after leaving his job as a bartender in downtown L.A. -- he approached his car and saw a group of people trying to steal his c.