A man shot and killed by Dallas police earlier this week was a familiar figure in North Texas law enforcement and part of the security detail for US Rep. Jasmine Crockett, CBS News Texas reported, citing sources.Multiple law enforcement sources told CBS News Texas the man, known publicly as Mike King, used aliases while running a business that placed officers in off-duty jobs.King was killed Wednesday night after a standoff with Dallas police SWAT officers. Police said he fled into a hospital parking garage, barricaded himself inside a vehicle, and was forced out by tear gas before pulling a gun on officers.Sources said he was wanted for impersonating a law enforcement officer and claimed to be one while operating Off Duty Police Services, an online platform connecting North Texas officers with off-duty work. Authorities did not release his real name.Images obtained by CBS News Texas showed King standing close to Crockett at events and on the campaign trail during her recent run for a US Senate seat. Sources said he oversaw teams of security officers at several downtown Dallas hotels and at his church.Law enforcement sources also said King drove a replica undercover police vehicle and used licence plates stolen from cars outside a military recruiting office. His background, which sources said included a criminal history, raised questions about how he managed extra-duty jobs for police officers and secured a high-level security role for a sitting member of Congress.Documents obtained by CBS News Texas showed a person named Mike King received payments for “security services” from Crockett as recently as last year.