The Montgomery County Ethics Commission yesterday rejected a request by Police Chief Charles A. Moose to parlay his central role in October's sniper manhunt into a book and movie deal.

In a stiffly worded six-page ruling, the commission said Moose's for-profit ventures would violate "bedrock principles" of county ethics law.

"It is not in the best interest of the County to allow its employees to trade on their government activities for private gain in such a direct and immediate fashion," the five-member panel ruled. "These principles are at the core of the prohibition against using the prestige of one's office for private gain."

The ruling added that neither Moose nor County Executive Douglas M. Duncan, who had asked the commission to make an exception for the chief, "has convinced the commission that this situation is a good platform to begin waiving those principles."

A request by Moose to operate a private consulting business, to provide advice on crisis management and leadership, is still pending before the commission.

Moose, who was called to active duty late yesterday with the D.C. Air National Guard, could not be reached for comment. But his attorney said he found the opinion "astounding."

"I think the commission's decision is seriously flawed," Ronald Karp said. "They concede that the county executive has decided that this is in the best interest of the county. But these five unelected members of this commission say, 'No, we know better.' "

Karp said the chief has not had time to weigh his response. One option, he said, is to file an appeal with Montgomery County Circuit Court.

Moose has said his project is a chance to help others by telling his up-by-the-bootstraps life story and by revealing how grit and teamwork led to breaking the case that terrorized the region and captivated the nation.

He said he decided to write the book after being besieged with offers during the grueling hunt for the men who killed 10 people and wounded three. In January, Moose signed a contract with Dutton, a New York publishing house, to produce a book tentatively titled "Three Weeks in October: The Manhunt for the D.C. Sniper," scheduled for a fall release.

Yesterday's decision throws that agreement and his movie deal with a Hollywood production company into doubt. (Dutton publicity director Lisa Johnson did not return calls seeking comment yesterday.)

It has also renewed speculation that Moose will leave the chief's post rather than relinquish the projects. Duncan (D) has warned that a denial from the ethics commission could prompt Moose to look elsewhere for work.

In a March 12 letter to the commission, Duncan urged the members to grant Moose a waiver, arguing that "the most obvious benefit would be retention of this high-ranking employee." Yesterday, Duncan said it remains a concern for him. "If the choice is one or the other, I want him to remain as chief," he said.

In his appeal to the commission, Duncan also argued that a book by Moose "would allow County citizens to better understand their police" and that the publicity generated by Moose's projects would aid in the county's recruiting efforts.

But commission members were "not persuaded by the County Executive's reasoning because there may be more harm than good in granting the waiver."

A waiver now "could lead to undesirable behavior" in the future, the panel said, such as employees "jockeying for position" during high-profile incidents in hopes of winning fame and fortune.

The commission also expressed concern about the potential for a publisher to use money to pressure Moose into revealing confidential details about the sniper case that, if publicized, could be harmful to the prosecution of the suspects. Moose has pledged to vet the book with prosecutors. Duncan said yesterday he is "disappointed in their ruling" but does not intend to ask the County Council to carve out a special exception for Moose. That idea began to look increasingly complicated in recent weeks. Council President Michael L. Subin (D-At Large) said yesterday he would have had to recuse himself from debate on the matter because he works with Karp's law firm, though not on the Moose case. And several council members said publicly they wanted no part of it.

"We can't write a law for just one person," said Council Vice President Steven A. Silverman (D-At Large). Council member Phil Andrews (D-Gaithersburg) agreed, saying that while he supports the chief, this decision was best left to the ethics commission.

"Would I be inclined to intervene?" Andrews pondered. "No. I think the ethics commission is established for just this sort of situation. There would have to be an extraordinary reason to, in effect, overrule their conclusion. And I don't see that here."

Moose's is one of several books about the sniper case in the works, including one by reporters at The Washington Post.

Chief Charles A. Moose is awaiting a ruling on plans for a consulting firm.