The County Commissioners approved Sigler's hiring on a 4-1 vote.
Sigler has not yet formally resigned from the Charles Town Police, but said he planned to notify the chief today.
Aldridge declined to comment, saying he had not been formally notified of Sigler's plan to resign.
Sigler is the second officer involved in the internal affairs investigation to resign after being cleared of wrongdoing by the Civil Service Commission. Officer Joe Forman resigned Sunday.
"Basically I don't feel I can work under the leadership that's there after what's happened in the recent past," Sigler said Thursday.
Sigler had been on paid administrative leave while Aldridge tried to fire him and Forman from the department.
The chief accused the two of lying under oath at a grievance hearing about whether Sigler was present when Aldridge yelled at police secretary Valerie Weaver on Aug. 21, 1997. Aldridge believed Weaver was attempting to have a friend's traffic ticket dropped.
Sigler and Forman argued that they did nothing wrong.
None of the witnesses disputed that Aldridge and Weaver were involved in an altercation, but several of the officers testified they did not believe Sigler was there at the time. Sigler, Weaver and Forman testified that Sigler walked into the office during the altercation.
Sigler said it was difficult to be the subject of an investigation, but he felt vindicated by the Civil Service Commission's ruling.
"I have a good name as a police officer and I wanted to keep my good name," Sigler said.