From this:

The leaders of the U.S. Border Patrol's rank-and-file agents have unanimously voted a no-confidence resolution against Chief David V. Aguilar, citing, among other things, his willingness to believe the "perjured allegations" of criminal aliens over his own agents.

The resolution won endorsement from all 100 top leaders of the National Border Patrol Council (NBPC), which represents all 11,000 of the U.S. Border Patrol's nonsupervisory field agents, and targeted Chief Aguilar's lack of support for field agents, several of whom have been prosecuted on civil rights grounds involving arrests of illegal aliens and drug-smuggling suspects.

[...they're upset Aguilar hasn't spoken out against the Ramos/Compean case... ...Aguilar defends himself through spokesman Xavier Rios...]

[Rios] said the two agents "shot a man and made an effort to cover it up."

Even when defending his boss he might have made things worse, since it appears to be an open question whether they tried to cover it up or not.

...[The resolution] accused the chief of "shamelessly promoting amnesty and a greatly expanded guest-worker program as key elements of the solution to the illegal immigration crisis" despite intense opposition from front-line agents "who risk their lives enforcing our nation's immigration laws."

"Instead of maintaining their traditional neutral advisory role, these high-level managers have become advocates for the administration's ill-conceived political agenda that includes amnesty for millions of illegal aliens," Mr. Bonner said.