"The grieving process can take years, unfortunately, and symptoms of PTSD can also take before they start to settle as well," said San Francisco clinical psychologist Dr. Andrea Zorbas, who is founder of Therapy Now. "So this is going to be something that is going to be needed ongoing."
A hurdle could be the stigma of seeking mental health services. Loved ones should be on the lookout for symptoms of depression, insomnia, anxiety, feelings of survivor's guilt and flashbacks.
"If you notice something with your loved one that you bring it to their attention, that we try to demystify and destigmatize going to get mental health treatment," said Leslye Tinson, a lecturer of psychology at San Jose State University.
RELATED: How to help San Jose shooting victims and their families
Psychologists say friends also need to reach out to offer support in a very targeted way.
Tinson suggested this approach. "Offer what you can provide instead of asking the grieving person, 'what do they need from me?' As a friend say, I can bring meals to your house on Wednesday and Friday. Is that OK?"
In the VTA case and others, victim families will never see closure since the alleged shooter is dead and is not facing prosecution. However, the case likely will be examined to see if warning signs went undetected. Such analysis can be difficult.
RELATED: These are the 9 victims of the VTA attack
"When you look at all these mass shooters, there is no common thread. There is no risk profile," noted Dr. Hans Steiner, professor of psychiatry and behavioral sciences at the Stanford School of Medicine. "There's not one thing that predicts they can be mentally ill. It can be in the majority. They're not." Dr. Steiner studies mass casualty events and is writing a book.
Intervention is complicated by privacy laws and false assumptions that mental illness is a root cause.
"Many mentally ill people commit serious crimes. Many non mentally ill people commit crimes," said Prof. Robert Weisberg, Ph.D. J.D., co-director of the Stanford Criminal Justice Center. "There's no very clear correlation between mental illness and crime."
Privacy laws can be amended to allow disclosure of mental health records as they are not Constitutional rights, according to Prof. Weisberg. However, he said "legislators are going to be very loath to intervene in them too much."
RELATED STORIES & VIDEOS:
- What we know about suspected VTA railyard shooter Sam Cassidy
- EXCLUSIVE: San Jose shooting widow remembers 'soulmate' of 22 years
- Families share touching memories of VTA shooting victims during San Jose City Hall vigil
- Witness says gunman targeted those he worked directly with at VTA
- EXCLUSIVE: VTA mass shooting witness describes 'mass of bodies,' says gunman had specific targets
- Suspected VTA shooter's ex-girlfriend describes relationship as abusive, says he was 'mentally not stable'
- San Jose VTA attack is 18th mass shooting in California this year
- VTA light rail operator killed while helping coworkers hide
- VTA rail yard, Gilroy Garlic Festival among deadliest mass shootings in Bay Area history
- Officials share emotional reactions to SJ rail yard tragedy
- Local resources for survivors and victims of gun violence