By Jenni Bergal

At an Iowa mall, a security guard allegedly shot and killed a woman who worked at a children's museum there. At a Kentucky distillery, a security guard accepted money from thieves to look the other way while they stole more than $100,000 in expensive whiskey. And in a Virginia hospital, a 64-year-old man suffered a serious head injury and later died after a violent altercation with a security guard.

Recent incidents like these have drawn fresh attention to the screening, training and state oversight of private security officers, and have prompted some legislators to push for stricter regulation _ efforts that have been largely unsuccessful this year.

"We've got to feel comfortable that people who have a badge on are, in fact, trained _ and trained well," said Michigan state Sen. Darwin Booher, a Republican who sponsored a set of bills, still pending, that would update regulations on security guards in the state.

About 90 bills were introduced in state legislatures this year dealing with the licensing and training of security officers or requirements for security companies, according to Steve Amitay, director of the National Association of Security Companies (NASCO), an industry group. In recent years, similar numbers of measures have been proposed. None of this year's bills that would have substantially toughened state requirements was enacted, Amitay said.

"In some of these states, it's a very anti-regulatory environment and they think any additional regulation on businesses or people performing services is bad," Amitay said. "With other folks, it's a resource issue. For the state to start regulating an industry and requiring licenses requires initial appropriations and startup costs."

In Connecticut, a bill that would have required security guards to get more training died in the Senate. In Washington state, a measure that would have mandated FBI criminal background checks for all applicants never made it to the House floor.

In California, Democratic Gov. Jerry Brown vetoed a bill that would have made bouncers and plainclothes guards subject to the same licensing requirements that apply to private security officers.

Forty-one states, plus the District of Columbia, license security officers, but requirements vary greatly from state to state. Alaska, for example, mandates 48 hours of training initially, plus another eight hours in firearms training for armed guards. South Carolina requires four hours of training and an additional four for those who carry a gun.

While nine states _ Colorado, Idaho, Kansas, Kentucky, Mississippi, Missouri, Nebraska, South Dakota and Wyoming _ do not license security officers at the state level, some cities within them do, according to NASCO. Mississippi does require that guards get a separate permit to carry a gun. And 22 states have no training requirements for unarmed security guards; 15 of those have none for armed guards, either.

"It's a hodgepodge. It's an extreme variety of approaches," said Charles Nemeth, a professor at John Jay College of Criminal Justice who directs its Center for Private Security and Safety. "Some are better than others; some are nonexistent."

More than 1 million security guards work in retail stores, hospitals, sports stadiums and other locations, according to the U.S. Bureau of Labor Statistics. They typically are responsible for protecting property, enforcing rules, conducting security checks and deterring criminal activity, and had a median salary of $23,970 in 2012.

Most work for a security company that contracts its services. Others are hired directly by a business or corporation.

While the vast majority don't carry weapons, those that do have raised special concerns. A 2014 investigation by the Center for Investigative Reporting and CNN found poor oversight and little accountability of the armed guard industry. Twenty-seven states did not check whether armed guard applicants were in a federal database banning them from carrying a gun and nine did not conduct federal criminal background checks, the investigation revealed.

There are no federal standards for training security officers _ armed or unarmed _ so it's left to the states. Basic training usually involves learning how to administer CPR, the proper use of force, how to deal with the public and fill out reports, and how to report suspicious activities and interact with police.

Sandi Davies, director of the International Foundation for Protection Officers, a nonprofit that gives training certificates to security guards, said states should require at least 40 hours of basic training _ most don't.

"We want a more trained and skilled officer to protect our premises. They need to be able to identify threats," Davies said. "I can't for the life of me think that anyone should be in a position of authority without at least 40 hours of training."