In today's fifth episode of "A Nation at Gunpoint," we'll be focusing on the link between mental disease and gun violence. We'll also be looking at what the perspective is from the US government's on this issue.

A growing number of gun crimes in the United States are committed by people suffering from mental health issues.

In August 2015, Bryce Williams, a reporter fired from WDBJ-TV in Virginia, shot two of former colleagues during a live broadcast.

Both Alison Parker and Adam Ward died after the incident. Bryce Williams later shot himself after being surrounded by police.

He was allegedly suffering from severe persecution delusion before the tragedy, but it was something none had noticed or taken steps to treat.

"One of the problem in this country has in the last few decades define people before these kinds of things happen," siad David Keene, former president of National Rifle Association.

In July 2012, the US was stunned by a mass shooting at a cinema in Aurora, Colorado. Twelve people were killed and seventy others were injured. The shooter, James Egan Holmes, had also exhibited signs of abnormal behavior before the tragedy.

"There are so estimated that perhaps 15 percent of Americans have some form of mental illness. There is not enough to treat all those effectively," Ron Hosko, former FBI assistant director.

How mental health issues have an impact on criminal behavior is still a controversial topic. More research needs to be done to find a definite link.

However, before relevant research can be conducted, the US medical research field has to overcome a number of obstacles.

Georges Benjamin, from the US Public Health Service, has been making efforts to reduce gun crime from a public health perspective.

"More than 20 years ago, the Disease Control and Prevention did find some violence-related research in this country," said Georges Benjamin, executive director of US Public Health Association.

20 years on and Georges Benjamin has still made little to no headway with his research.

Meanwhile, the US government has made attempts to include information about mental health issues into the system to determine a person's suitability to purchase a firearm.

But that idea doesn't have the support of Congress.

"For those in congress so often... For your money for your mouths," said Barack Obama, US president.

In fact, guns have been used more frequently in suicide cases. In 2013, around forty thousand people in the US killed themselves, and more than half of those used a gun to end their life. More work still needs to be done by the government to tackle shootings and suicides which are linked to mental illness.

Tens of thousands of guns would be stolen each year in the United States, and most of them were used in crimes. So in order to reduce gun crimes, a new kind of smart guns has surfaced. In tomorrow's sixth episode of "A Nation at Gunpoint", we will be looking at what the smart guns are and their differences with the ordinary ones.