( CNN ) -- The man that prosecutors say is behind the stabbing deaths of four homeless men in Southern California now stands accused of the brutal killing of a mother and brother of an old friend , authorities said . The latest allegations against Itzcoatl Ocampo , 23 , were made public Friday , shortly after authorities dropped charges against the friend , Eder Herrera , in the killings . Ocampo will be arraigned Monday on charges he stabbed to death 53-year-old Raquel Estrada and her 34-year-old son , Juan Herrera , Orange County District Attorney Tony Rackauckas told reporters . `` This case has expanded from murdering random , vulnerable strangers to murdering people he knew , '' he said . Authorities say Estrada was stabbed more than 30 times and Herrera more than 60 times on October 25 , their bodies left in pools of blood inside their Yorba Linda home . Herrera , 24 , was arrested a day later in large part because of eyewitness statements and surveillance video from a nearby store that showed someone resembling Herrera in the area at the time of the killings , Rackauckas said . But the brutality and similarity of the attacks caught the attention of a law enforcement task force created to investigate the homeless killings . It is the latest twist in the case that began on December 20 when the body of a homeless man who had been stabbed more than 40 times turned up in Orange County . Herrera and Ocampo , an Iraq war veteran , had been friends since their high school days , Rackauckas said . The two lived about a mile apart , he said . The district attorney did not comment on a possible motive in the murders of Estrada and her son . While charges against Herrera were dropped , he remained in custody at the Orange County jail late Friday on an immigration hold , authorities said . Ocampo has been in custody since his January 13 arrest on suspicion of killing 64-year-old John Berry outside a Carl 's Jr. in Anaheim , authorities said . His arraignment in the homeless killings has been postponed until February 17 . Ocampo is also accused of killing James McGillivray , 50 , who was killed December 20 ; Lloyd `` Jimmy '' Middaugh , 42 , who died December 27 and Paulus `` Dutch '' Smit , 57 , killed on December 30 . Ocampo served in the Marines from July 2006 until July 2010 , and was deployed to Iraq for six months in 2008 , according to Marine service records . He completed his service , with the rank of corporal , with the 1st Marine Logistics Group at Camp Pendleton , south of Orange County . CNN 's Greg Morrison and Rosalina Nieves contributed to this report .
Itzcoatl Ocampo will be arraigned later on the new charges , the district attorney says . Ocampo , 23 , is accused of the brutal shooting death of Racquel Herrera and her son . Authorities say Ocampo and Herrera 's son , Eder Herrera , are friends .