Sources tell PEOPLE that Cornell was planning future concert dates the week of his death, among other things, and couldn't have been suicidal

Chris Cornell‘s behavior in the week leading up to his May 18 death is proof that the Soundgarden rocker wasn’t suicidal, a family source tells PEOPLE.

Cornell was found dead in the MGM Grand Detroit following Soundgarden’s performance at the Michigan city’s Fox Theatre. His death was ruled a suicide by hanging.

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In the weeks following, Cornell’s family — who have struggled to come to terms with the rocker’s death — said that they didn’t believe him to be suicidal and think that the prescription drugs found in his system may have impacted his mental state.

“It’s hard to overstate how unpredictable the effects of mixing various mind-altering substances can be,” Dr. Benjamin Nordstrom, addiction psychiatrist at Phoenix House, tells PEOPLE. “Some of these combinations, especially those that involve sedative drugs, can lead to levels of impairment that are far out of proportion to what would have happened if the drugs were taken separately. In addition, suicide is nearly impossible to predict for families or professionals alike. Anyone struggling with substance use issues should seek help.”

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The insider tells PEOPLE that on May 4 – just two weeks before Cornell’s death – he pushed his flight from Atlanta, Georgia, back a day over safety concerns about flying in inclement weather.

The next week, on May 9, Cornell made a similar choice after hearing his flight from Tuscaloosa, Alabama, was delayed due to mechanical issues. The source says that Cornell was nervous to fly due to potential plane issues, and instead drove a rental car over seven and a half hours to his intended destination.

“Clearly someone who was so hesitant and fearful to fly in these situations valued their life,” says the source. “These are not indications of someone with no regard to their well-being.”

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Further, the source says Cornell made plans to perform at a concert for World Refugee Day on June 20th with UNHCR.

On the night of his death, the insider adds that Cornell asked both security and an engineer to help him get his Apple TV system to work around 11:45 p.m. Says the source, “Chris was so adamant about getting his TV to work he called for backup assistance when security was unable to fix it. Someone so persistent about fixing a TV so they can watch their favorite show, focusing on something so mundane, is not a sign of someone planning to take their life.”

A completed toxicology report for Cornell released earlier this month and obtained by TMZ confirmed that the rocker had several drugs in his system at the time of death, including Naloxone (Narcan), Butalbital (a sedative), Lorazepam (Ativan), Pseudoephedrine (a decongestant) and barbiturates. The Narcan, used to reverse opioid overdoses, was reportedly administered by EMTs arriving on scene.

Cornell had ingested four tablets of the Ativan, which can cause worsening depression and thoughts of self-harm in rare cases.

“Many of us who know Chris well, noticed that he wasn’t himself during his final hours and that something was very off,” wife Vicky Karayiannis Cornell said in an earlier statement to PEOPLE.

“We have learned from this report that several substances were found in his system. After so many years of sobriety, this moment of terrible judgement seems to have completely impaired and altered his state of mind. Something clearly went terribly wrong and my children and I are heartbroken and are devastated that this moment can never be taken back.”

She added, “We very much appreciate all of the love we have received during this extremely difficult time and are dedicated to helping others in preventing this type of tragedy.”

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The family source notes that even during Cornell’s “darkest days” of drug abuse – when he admitted himself into Promises treatment center in Malibu in 2002 – he did not “reveal suicidal tendencies.”

“Nor did he show any signs of depression in the final days leading up to his passing,” adds the insider.

In a statement immediately following Cornell’s death, his wife asserted, “I know that he loved our children and he would not hurt them by intentionally taking his own life.”