Vallejo police said there was no evidence of felony animal abuse, according to KABC.
Solano County Animal Control found no collars, microchips or other ways to identify the dogs.
The investigation might have been hampered from the start because Peters called a private number of an off-duty officer which led to a six-week delay.
"In this case, had we got the call when she first reached out to us in February, the scene would have been better preserved and we would have been able to collect far more evidence," Christine Castillo, spokeswoman for the Solano County Sheriff's Office, told KABC.
Jami Bishari hoped for closure after her 6-year-old Chihuahua TT went missing in July. She is concerned that whoever killed the dogs could continue to do so, or escalate the behavior.
"You might want to say this isn't a murder, but what is this person going to do a year from now or two years from now when dogs aren't enough?” Bishari said.