Sheriff's deputies' cars sit in front of the house of where gunman Mohammod Youssuf Abdulazeez lived in Hixson, Tennessee, Friday, July 17, 2015. Reuters

As the FBI investigation to find the motives for last week's killing of five servicemen in Chattanooga, Tennessee, continues, the shooter's diary -- along with his parents' interviews with authorities -- showed he struggled with mental instability, drug use and money problems and faced an appearance in criminal court, a family representative told ABC News Monday. The diary reportedly showed that 24-year-old Mohammod Youssuf Abdulazeez wrote about suicidal thoughts and "becoming a martyr" after losing his job in 2013 while he abused drugs, the family representative told the network.

Abdulazeez opened fire Wednesday at two military facilities in Chattanooga, killing four Marines and fatally wounding a naval officer, before being killed by police. His diary reportedly suggested that he had suicidal thoughts and considered becoming a "martyr" while his life spiraled downward as he abused sleeping pills, painkillers, marijuana and alcohol. The family's representative told ABC that he most recently had difficulty dealing with a 12-hour overnight shift and started taking sleeping pills. Abdulazeez was also in significant debt and considering filing for bankruptcy.

A mugshot of Muhammod Youssuf Abdulazeez from a DUI charge in April in Hamilton County, Tennessee, is shown n this handout image provided by the county sheriff's office. Reuters

A statement Saturday from the gunman's family said he suffered from mental illness. "For many years, our son suffered from depression," the statement read. "It grieves us beyond belief to know that his pain found its expression in this heinous act of violence." The family described the shooter as "not the son we knew and loved."

With more than 30 FBI agents scheduled to arrive in Chattanooga Monday, Abdulazeez's parents reportedly told the bureau there were no outward signs of radicalization. The family representative told ABC News Sunday that Abdulazeez, a devout Muslim, didn't display signs of radicalization but "was susceptible to bad influences” and was affected by news reports about “children being killed in Syria.”

Abdulazeez, a Kuwait-born Jordanian, spent several months in Jordan, reportedly to try to stop his drug and alcohol habit. The naturalized U.S. citizen lost a job in 2013 at an Ohio nuclear power plant after failing a drug test. Three months before the shooting in Chattanooga, Abdulazeez was arrested on April 20 -- the day popularly celebrated by marijuana enthusiasts -- and charged with drunk driving after an officer noticed a smell coming from the car. His court hearing for the case was to be July 30.

Investigators were still piecing together the days leading up the shooting. Abdulazeez rented a silver Ford Mustang, which he bragged about, and he took a friend Tuesday from the local mosque on a "joy ride" until 3 a.m., the family representative told ABC News. He did not sleep at his parents' house for the next two days, and the FBI was reportedly attempting to retrace his steps.

Abulazeez owned a number of guns, often going hunting and shooting at ranges, and FBI agents recently focused on a Walmart in Hixson, Tennessee, where he bought ammunition July 11, officials told ABC News. Two men were reportedly being sought for questioning but were not believed to be accomplices in the killings.