The growth of private security has expanded from an estimated 300,000 employees in the industry in 1969 to an estimated 2 million people. The private security industry is now twice the size of public law enforcement. Moreover, public law enforcement resources have not proportionally increased despite growth rates in population and crime. Police officers have traditionally viewed private security employees as inadequately trained and paid. There has also been some concern that the private security industry may usurp important aspects of public law enforcement and erode citizen contacts that bond them with police in a common alliance. These concerns, however, have not been realized, and some mutually beneficial relationships between private security and law enforcement have been established. Areas of cooperation include record collection and dissemination, drug law enforcement, and the provision of training programs by private firms to public law enforcement agencies. The scope of private security changes constantly. Proprietary or corporate security encompasses such sophisticated and diverse concerns as asset protection, loss prevention, countermeasures for industrial espionage, drug testing, extortion, product tampering, and communications security. Many private security investigations involve credit card theft, shoplifting, embezzlement, computer hacking, and employee theft. 6 references.