Read more about this story from CNN affiliate WCBS-TV.
New York (CNN) -- A New York man accused of drugging, smothering and dismembering an 8-year-old Brooklyn boy has been deemed mentally competent to stand trial, attorneys revealed in court Thursday.
Prosecutors say Levi Aron abducted the boy, Leiby Kletzky, from his Brooklyn neighborhood on July 11. The accused then took Leiby to his apartment and killed him, they contend.
Aron pleaded not guilty Thursday in a Brooklyn courtroom.
Aron did not enter a plea at his arraignment last month, and he was under a suicide watch. A mental evaluation that his attorneys asked be conducted on their client was revealed in court Thursday.
Kings County District Attorney Charles Hynes applauded the decision.
"Now that Mr. Aron has been found fit to proceed we will move forward expeditiously to bring his case to trial. I want to reaffirm that this case will go to trial and that there are absolutely no circumstances which would lead me to accept a plea bargain," Hynes said.
New York City's chief medical examiner said that Leiby died after being drugged and then smothered.
The autopsy results for Leiby listed a cocktail of four prescription and over-the-counter drugs in the boy's system: cyclobenzaprine, a muscle relaxant; quetiapine, an antipsychotic drug; hydrocodone, a pain medication; and acetaminophen, the drug found in Tylenol, according to the medical examiner's office.
Leiby disappeared while walking home alone from summer day camp. Police located human remains in Aron's freezer during a search of the Brooklyn neighborhood as well as in a trash bin.
Both Aron and Leiby are members of the borough's close-knit Orthodox Jewish community, although police say it doesn't appear that they knew each other.
"Everybody says, 'We're not going to talk about it,' but how can you not talk about it? How can you not talk about a tragedy that has affected every single family," Assemblyman Dov Hikind told CNN affiliate WCBS-TV.
Authorities have detailed some of the evidence they allege links Aron to the kidnapping and killing -- including extensive video footage that shows Leiby talking to a man and following him to a brown car authorities later traced to Aron.
Detectives later concluded that Aron was also the man they saw in the video footage.
New York Police Commissioner Ray Kelly said last month that Aron told authorities he was sorry for the trouble he has caused. Statements made by the suspect indicated that he kidnapped Leiby and, as the neighborhood search for the boy intensified, he panicked and killed him, Kelly said.
"His mental capacity is a question for the doctors," Hynes said.
Aron's attorney at the time of his initial arraignment said he hears voices and hallucinates.
"He's been hearing voices for quite some time," Gerard Marrone told reporters last month, adding that Aron tries to silence the voices by listening to music. "He listens to it with earphones and he listens to it very loud, and that helps him quell some of his voices."
Marrone has since resigned from the case.
"I have sincerest concerns about the defendant's mental state and his cognitive abilities," said Pierre Basile, who is representing Aron.
The commissioner called the case "heartbreaking."
"Obviously, in this business you see a lot of violence, but there's usually some sort of irrational twisted logic that's given to why a violent event took place," Kelly said.
"Here, I mean, it's just, it defies all logic and I think that's what's really so, so terribly disturbing about this case. There's absolutely no reason. There's nothing more innocent than an 8-year-old child."
On the day he disappeared, Leiby was supposed to meet his parents after walking seven blocks from day camp, but he became lost and asked the suspect for directions, Kelly said.
Surveillance video showed Aron entering a dentist's office while Leiby waited for him across the street for seven minutes, Kelly said.
Aron claims he took Leiby to a wedding in Monsey, New York, and then brought him back, Kelly said. Police said Aron went to the wedding, but they have not been able to confirm that Leiby went with him, as no one has said they saw him.
According to Kelly, police showed up at Aron's third-floor attic apartment at 2:40 a.m. July 13 and asked him about Leiby's whereabouts. The suspect pointed them to the kitchen, where blood was visible on the freezer handle. Inside the refrigerator was a cutting board with three blood-spattered carving knives, Kelly said.
Remains were found in Aron's freezer and in a trash bin more than two miles away, wrapped in a black plastic garbage bag inside a suitcase, Kelly said.
Aron was a clerk at a maintenance supply company, authorities said. His only known criminal summons was for urinating in public last year.
CNN's Jesse Solomon, Nina Raja, Nina Golgowski and Leigh Remizowski contributed to this report.