CALIFORNIA CITY, Calif. (KERO) — Authorities have asked multiple people to take a lie detector test in the missing California City toddlers case.

California City Police Chief Jon Walker confirmed Saturday, that individuals "close to the investigation" were asked to take the test at some point after 3-year-old Orson West and 4-year-old Orrin West were reported missing on Dec. 21.

Walker did not disclose who those individuals are, when they were asked to take the test, or whether anyone took or denied the test.

This comes after Walker previously confirmed that authorities asked the adoptive parents of the missing brothers to take a lie detector test, the day after the boys were reporting missing. Walker did not confirm whether the parents took or denied the test.

Though lie detector tests are not admissible in California courts, Walker says they are a useful investigative tool.

There has been no suspect or persons of interest named in the case so far.

A vigil for the boys is planned for 6 p.m. Monday in the 10000 block of California City.