Los Angeles ( CNN ) -- Slain Santa Monica gunman John Zawahri left behind a note on his body apologizing for killing his father and his brother and hoping his father 's estate would support his mother , police said Friday . Zawahri , 23 , who lived with his father in a house that was also set afire , wrote a three- to four-page handwritten letter in which he spent a `` larger '' measure of it saying good-bye to his friends than talking about his family , police said . Authorities described the tone of the letter as `` conversational talk '' without `` overall hatred to anything , '' a police spokesman said . `` He was sorry for having killed his father . He was sorry for having killed his brother , that he hoped his mother would be looked after financially and that she would receive financial recompense from the father 's estate , and he said goodbye to his friends , '' said Santa Monica Police Chief Jacqueline Seabrooks said . `` It was more of a farewell , '' Seabrooks added . Santa Monica shooting survivor : 'Thank God , I 'm alive ' No motive to his alleged shooting -- in which a total of five people were killed -- was given in the note , she said . Police revealed Friday that Zawahri tried a buy a weapon in 2011 , but the U.S. Justice Department issued a notice stating that Zawahri was ineligible to buy a firearm . Seabrooks said the Justice Department denial `` may have something to do with our contact with him in 2006 , but I 'm not sure . '' Police had contact with Zawahri in 2006 , but because he was a juvenile then , authorities were n't releasing further information , the chief said . Zawahri had suffered mental health issues , a law enforcement source with knowledge of the investigation told CNN last week . A couple of years ago , he was hospitalized for treatment after allegedly talking about harming someone , according to the official . It 's not clear whether the California state government or his family committed him for treatment or whether he committed himself . It 's also unclear under what circumstances he was released . Zawahri used firearm components to construct a rifle that is illegal to possess , Seabrooks said Friday . Shooting takes 5 lives . He allegedly fired 100 or fewer rounds during a shooting rampage across Santa Monica , adjacent to Los Angeles , that ended at the Santa Monica College , where police shot him to death , authorities said . He was armed with multiple guns and about 1,300 rounds of ammunition , police said . When asked where or how Zawahri obtained the firearms used in the shootings -- especially after the Justice Department deemed him ineligible to buy weapons -- Santa Monica Police Sgt . Richard Lewis stated : `` That is a part of the investigation that we will not disclose . '' His father and brother died of gunshot wounds , and their bodies were found in the back of the father 's Santa Monica house , a police spokesman said . Their bodies were identifiable , `` and it 's not that they were burned beyond recognition , '' the chief said . Neighbors said the parents were divorced . The mother has spoken with investigators , but the police chief did n't elaborate further . Zawahri was unemployed and had n't attended Santa Monica College , where his shooting rampage ended , since 2010 , a police spokesman said Friday . Gunman previously hospitalized for mental health .
Police are n't disclosing how Zawahri obtained guns used in rampage . Slain gunman John Zawahri hopes his father 's estate will support his mother . The handwritten letter `` was more of a farewell , '' police chief says . U.S. Justice Department said he was ineligible to buy a weapon in 2011 , police say .