Virginia Tech: What exactly do campus police do?
Campus police can have many of the same rights and responsibilities of a municipal department - but they serve a more insular community.
In November, officer John Pike made international headlines when he shot a bright-orange stream of pepper spray at protesting students at the University of California, Davis.
Mr Pike, a member of the UC Davis campus police, was kitted in full riot gear as he sprayed the students at close range.
It wasn't the first time campus police have made headlines in the US. A grand jury report on the Penn State sex abuse scandal revealed that in 1998, campus police launched a lengthy investigation into allegations that assistant football coach Jerry Sandusky had molested a young boy.
And now a university police officer at Virginia Tech has been shot dead after making a routine traffic stop.
These officers are a far cry from the "rent-a-cop" trope some may think of when it comes to campus security. But they're not aberrations.
American universities - many of which are larger than the towns they call home - have increasingly turned to their own police forces to keep campuses safe.
While some campus security forces consist of hired students or hourly security guards, others consist of trained officers, sworn to uphold the same laws as other police officers in the state.
In many cases, these campus officers have the power to make arrests and conduct investigations. Some even carry guns.
"Gradually American universities, starting with the bigger, more progressive ones, have gone to not just dealing with the local police but instituting their own police on campus with full police powers," says Bruce Benson, police chief emeritus and associate professor of criminal justice at Michigan State University.
This trend was accelerated in 2007. That year, Virginia Tech was scene of another tragedy: a gunman on campus killed 32 people and injured 25 others before turning the gun on himself.
"College campuses really stepped up a lot after Virginia Tech," says Robin Hattersly-Gray, executive editor of Campus Safety Magazine.
The main difference between fully operational police forces on campus and ones found in nearby towns and cities lies not in operational powers, but the communities they serve.
"They have generally the same kind of duties, the same kind of responsibilities, but there's a greater focus on community policing as opposed to 'lock 'em up and book 'em'," says Ms Hattersly-Gray
"They're dealing with 17 to 25 year olds. They're not emotionally mature, the brain hasn't fully developed," she says. "To that end, campus police forces do more preventative education and programme development around drinking, drug use, hazing and sexual assault.
"When a police force is tied to a campus, they're expected to be more proactive and more involved in the community," she says.
Campus police often face criticism over whether they take crime seriously enough.
While they can work with local law enforcement agencies and government when an offence is committed, they report to bosses within the university administration.
"That's where it can get dicey," says Ms Hattersly-Gray.
"When campus police report to high-ranking university officials, it can show that safety and security is a high priority at the school.
"The problem is if the administration feels it's bad for business to accurately report crime. That's against the law."
Since the 90s, federal law has required campus police to report crime statistics to the US Department of Education.
They must also provide students and faculty both "timely warning" if there is a rash of unsolved crimes (say, a series of dormitory burglaries), and "emergency notification" in the event of a crime-in-progress, such as a campus gunman.
The 2007 Virginia Tech shooter opened fired in two separate locations: a dormitory and a classroom building. That lead campuses to re-evaluate their methods for protecting students.
"The whole concept of emergency notification really came about after Virginia Tech," says Ms Hattersly-Grey.
Still, campus police can take a softer touch when dealing with campus crime, especially when the criminals are the tuition-paying students at the university.
Mr Benson, a consultant for campus police at universities across the US, recalls one "high-priced, prestigious university" where a janitor who stole $200 (£128) worth of school supplies was fired and prosecuted.
A student caught stealing thousands of dollars of electronics received administrative sanctions, but was allowed to stay in school and was never formally charged.
"There can be a tendency for the university to keep things quiet, handling things administratively rather than taking it through the proper legal channels," he says.
Sexual assault is also a contentious topic on campuses, since alleged attackers are often students.
If found to be responsible, they may be suspended or ejected from campus, or may face academic, but not legal sanctions.
"That [approach], of course, is coming under fire," says Ms Hattersly-Gray.
When it comes to the use of force, there is less room for discussion.
"Every agency should have a written directive on the use of force, and that should govern the circumstances and provide guidance to agencies and individual officers," says Christopher Blake, associate director and campus preparedness project director for the International Association of Campus Law Enforcement Administrators.
UC Davis had several documents regarding the use of force.
"It is the policy of this department that officers will use only that amount of force that reasonably appears necessary, given the facts and circumstances perceived by the officer at the time of the event, to effectively bring an incident under control," reads one of their guidelines.
Whether Mr Pike acted reasonably has yet to be determined.
He, one other officer, and the campus police chief are suspended pending an investigation into the pepper-spray incident.
What is in part so confusing about the UC Davis incident is that campus police are often specifically trained to handle situations like the Occupy protests and other crowd control issues.
"When I worked in a city, we would have a big festival maybe once or twice a year that had 10,000 people.
"In a campus, you could easily have a 100,000 people at a football game each weekend, or 20-30,000 come to a basketball game," says Mr Benson.
"I dealt with more riot situations in a campus environment than in a city environment, and on campus we had training to minimize injury and maintain crowd control."
Campus protests are also nothing new, and most don't end up with widely circulated videos of pepper spray.
"This is not what happens with proper training and policies," says Scott Jaschik, editor of Inside Higher Ed.