(CNN) -- A teenage student is facing a first-degree murder charge, with police saying that he followed through on a plan to kill the principal of his small private school in Memphis, Tennessee.
Eduardo Marmolejo was charged in the death Wednesday of 49-year-old Suzette York, the Memphis Police Department said in a statement Thursday.
A detention hearing was held on Thursday, during which Magistrate Judge Sheldon McCall ordered the suspect held without bail and also ordered a mental evaluation, said Chief Probation Officer Barry Mitchell of the Memphis and Shelby County Juvenile Court.
Court-appointed defense attorney Autumn Chastain told reporters Thursday that "it's difficult for everybody right now."
"It's just a very serious allegation," Chastain said. "We need to know everything that's going on in the case."
Police said the suspect is 17 years old, while Mitchell said he is 16.
CNN normally does not identify juveniles charged with crimes unless the juveniles are charged as adults. However in this case police have released his name under a Tennessee law that allows them to publicly identify juveniles charged with first-degree murder. Once the police publicly identified the suspect, CNN and other national and local media have reported his name.
York was found Wednesday lying in a pool of blood at Memphis Junior Academy, according to the city fire department. Police, who responded to a call at 11:15 a.m., added that she was pronounced dead at the scene, after succumbing to "multiple stab wounds."
Memphis Police Director Toney Armstrong told CNN on Thursday that the suspect "has been carrying a grudge all summer long" because the previous school year he'd been switched out of a class that he liked.
"Basically, he conspired all summer as to how he was going to get revenge," Armstrong said.
According to Memphis police, Marmolejo told investigators "that he did not like (York) and that she had made him angry." Then he allegedly acted on his plans Wednesday, during the first week of school.
"He found himself alone in a classroom, ... and he attacked Ms. York, stabbing her multiple times resulting in her death," said Armstrong.
The city's police chief said authorities have no indication Marmolejo conspired with anyone, either in the planning or in the execution of the alleged crime.
He added, "From what we've been told, ... there were no red flags" to suggest the suspect posed a danger to others or to himself.
York, who had been the principal of the school since 2008, has a family in Memphis, said Marvin Lowman, communications director for the Seventh-day Adventist Conference in Goodlettsville, Tennessee. The school is affiliated with that church, said officials.
"It's tragic all the way around," Memphis Mayor A.C. Wharton Jr. said outside the school.
Former student Kristen Bridges described York as an exemplary biology and math teacher.
"Past the teaching, she loved God," Bridges told CNN affiliate WREG. "And she showed that in everything she did."
Marmolejo's next hearing, also in juvenile court, is scheduled for August 24, according to Mitchell.
CNN's Rick Martin contributed to this report.