A "death note" that named two Miami Central Senior High School teachers has left both afraid and upset with the administrator's response.

A Miami-Dade Public School District spokesperson told CBS News Miami Tuesday afternoon that authorities found no credible threat.

"To me, it's a death note with my name on it," Doreen Simpson, a Miami Central Senior High School teacher, said.

Simpson shared a photograph of a letter she found folded on a student's desk on Nov. 5.  When she opened it, Simpson saw the words "death note" scribbled in two places and the names "Ms. Johnson" and "Ms. Simpson" written on the bottom left corner, Simpson said.

The letter had clocks drawn next to each name, too.

"I'm having anxiety," Suzette Johnson, another Miami Central Senior High School teacher, said.

Simpson first took the letter to Johnson to warn her, Simpson said. Then, she told administrators and handed the folded letter to an assistant principal, Simpson said.

Six weeks later, both teachers feel let down by the investigators.

"No officer had a conversation with me," Johnson said.

"I feel like the people who should be protecting me from something that goes wrong in that building are not available to protect me," Simpson said.

Accused student back at school 

In a letter, the principal told the teachers that administrators followed protocol, performed a threat assessment and suspended the student for 10 days, Simpson said.  

Since that suspension, the student is free to pass by Johnson's room without any extra security, Johnson said.

Simpson took medical leave to avoid a similar situation.

"My thing is what about all the people that are left back (at Miami Central Senior High School)," Simpson said.  "What if this boy decides, 'Oh, okay, I got away with this, I can do something else.'"

A spokesperson for the district emailed the following statement to CBS News Miami.

"Miami-Dade County Public Schools (M-DCPS) is aware of an alleged threat reported at Miami Central Senior High. School administration responded swiftly and after investigating, the Miami-Dade Schools Police Department deemed the allegation not to be a threat. The incident was handled administratively in adherence to the Code of Student Conduct."