BOISE, Idaho - Idaho authorities killed four more elk Wednesday as part of an effort to destroy the animals that escaped last month from a private hunting reserve near the Wyoming border.

State officers, acting on Gov. Jim Risch's Aug. 7 declaration of a disease and gene-pool crisis facing wild herds, have shot 14 elk since the harvest operation began Saturday. At least four of the elk did not have ear tags identifying them as domesticated animals owned by Rexburg veterinarian Rex Rammell, who operates the Chief Joseph "shooter bull" reserve where between 75 and 160 elk escaped in mid-August.

State officials fear the farmed elk will breed with wild elk during the fall mating season.

Rammell has demanded the state stop shooting his elk and allow him to try to recapture them by baiting catch pens with grain and molasses. He has disputed claims his elk may spread disease or pollute the genetics of the area's wild herds, contending his animals are healthy "purebred Rocky Mountain elk" descended from Yellowstone stock.

Rammell has recovered about 40 head - including 10 bulls - but said Wednesday he can't round up more because of the state's intense hunting effort.

"They've scattered them everywhere," he told The Associated Press. "And if they're shooting elk without ear tags, then they're killing wild elk because all my elk have been tagged."

Fish and Game spokesman Niels Nokkentved said state shooters Wednesday killed a young "spike" bull, a mature bull with branched antlers, and two cow elk. Three of the four elk had ear tags; one of the cows did not.

"We're not sure whether the unmarked cow is wild or whether it was just never tagged by Mr. Rammell," said Nokkentved.

Additionally, Fish and Game officers interviewed two licensed archery hunters in the area for the bow-hunt season, who reported killing two other elk that also had ear tags. Those animals had not been verified as part of Rammell's herd by Wednesday evening.