Illegal immigrants reportedly comprise as much as one-fifth of the population of Fairfax County, a Northern Virginia sanctuary jurisdiction in the national spotlight for several murder cases involving illegal immigrant suspects.

An expert witness called to testify before Congress on the “Dangerous Consequences of Sanctuary Policies” told the House Judiciary immigration enforcement subcommittee Thursday that 1 in 5 Fairfax County residents are either in the country illegally or living with someone who is there illegally.