Jaynes and Cosgroves received pre-termination notices last week for their actions leading to the death of Breonna Taylor in March 2020.
The professional standards unit said Jaynes lied in his affidavit for the search warrant, claiming Taylor's ex-boyfriend, 30-year-old Jamarcus Glover, had been receiving packages at Taylor's address.
Jaynes claimed he had observed Glover running a "trap house" at a home on Elliott Avenue and believed Glover had been stashing drugs or money at Taylor's apartment to avoid detection from law enforcement.
No money or drugs were found at Taylor's home the night she was killed.
The letter also states that Jaynes was untruthful in swearing a US Postal Inspector advised that Glover had been receiving packages at the residence.
Gentry also noted that neither Jaynes nor his supervisors were present at Taylor's apartment when the search warrant was executed.
Cosgrove fired 16 rounds into Taylor's apartment on the night the search warrant was executed.
"I have determined you [Cosgrove] fired sixteen (16) rounds after Mr. Kenneth Walker fired one round," Gentry said. "Two (2) of the sixteen (16) rounds you [Cosgrove] fired were found in the body of Ms. Breonna Taylor. One of these rounds was the fatal round that killed Ms. Breonna Taylor."
In violation of standard operating procedure, Cosgrove failed to activate his body cam prior to the search warrant at Taylor's residence.
Both Jaynes and Cosgrove have the opportunity to appeal the decision within 10 days. If an appeal for review is filed, the LMPD Merit Board will schedule a public hearing to review the action set forth in each letter.
The River City FOP released a letter in response to the termination of Jaynes and Cosgrove:
"The FOP believes that the terminations of Detectives Cosgrove and Jaynes are unjustified. There is certainly no evidence in this case that policies and procedures of the LMPD were violated to the extent that warranted termination. Interim Chief Gentry not only made the wrong decision, but also sent an ominous message to every sworn officer of the Louisville Metro Police Department."
"The FOP will stand strongly and firmly with Detectives Cosgrove and Jaynes throughout the appeal process. After conferring with our members and their attorneys, the FOP will have no further comment at this time."