Tyler could not be reached for comment.
"I'll be sorry to see Shawn go," du Cellier said. "He and I get along very well. He's a fine, bright young officer. I'm going to miss him a lot."
Du Cellier said Tyler has agreed to keep working in Smithsburg on a part-time basis for about two months.
Tyler has been helping du Cellier, who took over as chief on Jan. 21, make the transition to his new job. Du Cellier used to work with Tyler in Berkeley Springs, W.Va., where du Cellier was chief and Tyler an officer.
Du Cellier said Tyler has had the support of the majority of people in town. "Only a few have spoken against him, and those are the people who had the opportunity to deal with him professionally, and didn't like it," du Cellier said.
The town has been advertising for a replacement for Tyler since he gave notice more than a week ago. Deadline for applications is April 3, but that could be extended, du Cellier said.
Du Cellier said four people have applied for the job, and another three or four have asked for applications. He said the town is looking for someone interested in the community policing concept.
"I was kind of hoping we could get a female officer," du Cellier said.
Starting pay will be between $23,000 and $25,000, depending on experience, town officials said.
Tyler's salary was paid through a grant. Town clerk/treasurer Betsy Martin said a small portion of that grant money is left. She said du Cellier is pursuing other grant sources to fund the remainder of the new officer's salary.