Shopping centers, stadiums and universities may soon have a new tool to help fight crime. A California company called Knightscope says its robots can predict and prevent crime. Knightscope says the goal is to reduce crime by half in areas the robots guard.

　　William Santana Li is the chief executive officer of Knightscope. He says these robot security guards will change the world.

　　"Our planet has seven billion people on it. It's going to quickly get to nine billion people. The law enforcement apparatus and security apparatus that we have globally is just not going to scale."

　　Mr. Li says his company's Autonomous Data Machines can become the eyes and ears of law enforcement.

　　"You want it to be machines plus humans. Let the machines do the monotonous computational heavy and sometimes dangerous work and let the humans do the strategic decision-making work so it's always working in tandem."

　　The machines are one and a half meters tall and weigh 136 kilograms. They do not carry weapons but thave day and night time video cameras able to turn 360 degrees. Mr. Li says they can also sense chemical and biological weapons.

　　Eugene Volokh is a law professor at the University of California. He says the machines have to be used in the right way. He says some people may become concerned about their privacy, especially in connection with the video recordings. Some people may worry that such recordings will appear on the Internet. Mr. Volokh says it will be interesting to see how state laws deal with this kind of surveillance video.

　　William Santana Li says there is a long waiting list for the robots in the U.S. At least 25 other countries are also intered in these robotic security guards.

　　I'm Jonathan Evans.

　　VOA's Elizabeth Lee reported this story from Los Angeles. Jonathan Evans adapted it for Learning English. Caty Weaver was the editor.