Cops are often in frequent contact with homeless people. Homeless individuals can be victims of crime, witnesses, associates of suspects, or suspects. They can also be a useful source of information about life on the streets, but only if the patrol cops who come across them treat them like human beings.

This is not to suggest all cops treat homeless people with contempt, but their interactions or concerns can range from, "I don't really care about them, as long as they aren't breaking the law" to "Get the hell off my beat!" to "I'll buy them a hamburger and a cup of coffee when I see them trying to stay warm on the corner."

Some officers at larger agencies will volunteer to create or work in so-called HOT or Homeless Outreach Teams, which may consist of cops, social workers, mental health clinicians, and grant-funded or religious-based homeless advocacy specialists. The goals for these teams, of course, is to break the hardened cycle of homelessness, their accompanying untreated mental illness problems, and their interconnected harmful relationships with drugs and alcohol. Many of these team members engage in what homeless advocate Ryan Dowd calls "empathic problem-solving."

Dowd is the executive director of Hesed House, the second largest homeless shelter in Illinois. He has written a new book, "The Librarian's Guide to Homelessness," specifically for library staffers, who clearly encounter the homeless regularly at their facilities. (Homeless people go to libraries because they are spacious, quiet, calm, stimulating, escapist, police-free, and usually inclusive.)

His book offers his decades of insight and dozens of practical tools for the library folks, but his words also serve as an entrance into a world few cops understand, or may not even care about. As such, his book is useful for patrol officers as well.

He offers these statistics about this at-risk, highly stressed part of our population:

National estimates are that 20% to 25% of homeless people are mentally ill. Of those, 70% have personality or other psychiatric disorders: bi-polar, depression, paranoid, borderline, antisocial, schizoid, delusional, psychotic). Many struggle with autism disorders. Many cannot learn from their repeated mistakes and are constantly in conflict and rude with nearly everyone who tries to help them because they cannot control their interactions. About 40% of homeless people struggle with alcohol abuse and 25% with drug abuse. On any given day in the United States, 22% of the known homeless population are children, 40% are women, and 35% are families.

Homeless people, says Dowd, often have traits, ideas, and characteristics that are similar to ours and yet widely different. Based on his long observations of people in his shelter, Dowd suggests many homeless:

• Grew up poor. (Often over many generations.)

• Speak differently. (We use a "formal register" with strangers or authority figures; they use a more "casual register.")

• Have a smaller vocabulary. (Limited education hurt their development as communicators. Simple words and clear commands to them work best.)

• Pay more attention to nonverbal cues. (They really read into body language, vocal inflection, tone perceptions, and volume.)

• Argue differently. (Their "anger ratio" is quicker and stronger, meaning they start loud and get louder, without much warmup.)

• View respect differently. (They see it as earned by fair, humane, and consistent treatment, not shouting, force, or punishment.)

• Look at time differently. (They don't have much more than a 24-hour time horizon. Beyond tomorrow is a long time for them.)

• Value relationships. (They are highly protective of their peers. They share lots of information with each other: safe libraries; fair or mean library staffers; fair or mean security guards or police; where to get free food, clothing, shelters.)

• Value their possessions. (They have an understandably strong emotional attachment to the stuff in their bags; it's often truly all they have in this world.)

• Look at space differently. (Every room they are in is the same as any other room and is to be used the same way, no matter where it is or who else is there.)

• Are funny. (They use gallows humor, just like cops.)

• Have experienced more trauma. (This includes repeated exposures to physical assaults, sexual abuse, evictions, abandonment, random or targeted violence, brain injuries, arrests, job loss, and relationship losses.)

• Are in more danger. (They cannot always protect themselves – especially when they are asleep. This population has a lot of accompanying and untreated PTSD problems.)

• Want to look scary. (Looking like a modern-day version of Charles Manson, says Dowd, is an intentional protective device to keep predatory people away from them.)

• Have had their IQs lowered. (Their education often stopped early and their lives on the streets have hurt their capacity to learn.)

• Are habituated to punishment. (Their usual and near-daily punishments—getting kicked out of a public place or threatened with jail—are not much of a deterrent to their behavior. Dowd says, "Homelessness is often the culmination of repeated punishment failing to change behavior.")

• Have less self-worth. (Most homeless people have almost none after six months of living on the streets and shelters, and having to resort to begging to survive.)

• Are treated like crap more. (Just about every non-homeless person looks down on them, literally, as they sit below normal human eye level on the sidewalk all day, asking for money.)

• Trust people less. (Their behavior and life circumstances have caused them to be abandoned by family members, employers, landlords, co-workers, friends, spouses, partners, or their children.)

• Value fairness. (They hate being singled out for punishment for rules that others get to break.)

None of this means that you should ever exchange your officer safety for your compassion when dealing with this population. But perhaps just having this knowledge as to the why and the how of homeless life can make your contacts with the homeless population easier on both sides.

Steve Albrecht worked for the San Diego Police Department for 15 years. He has written seven books on police officer safety and gun tactics. He can be reached at DrSteve@DrSteveAlbrecht.com or on Twitter @DrSteveAlbrecht