CHICAGO (CBS) — The suspect in the murder of a Walgreens clerk in Wicker Park appeared in court Wednesday for a bond hearing, where new details emerged about what happened moments before the killing.

A memorial for the victim, Olga Marie Calderon, was growing outside the store Wednesday with balloons lining the fence on the first day of opening since Sunday’s murder.

RELATED: Employee Fatally Stabbed At Wicker Park Walgreens | Sincere Williams, 18, Charged With Stabbing Employee At Wicker Park Walgreens To Death

Prosecutors say the suspect, 18-year-old Sincere Williams, prepared for the killing. CBS 2 has also learned that Williams was recently taken off of electronic monitoring for a separate burglary charge earlier this year when he was 17 – technically a juvenile.

Court documents say store surveillance video shows Williams leave covered in blood after stabbing Calderon, 32, 10 times on Sunday morning.

“The Defendant then turns around and leaves the Victim on the ground. The Defendant then calmly walks out of the Walgreens with the knife and calmly walks through the parking lot southwest out of view,” documents say.

Prosecutors also say he apparently had a change of clothes. Detectives say a combination of police and home cameras show him walking back to his home in a new outfit.

They say Williams threw the bloodied clothes in the bushes of a nearby house, but he could be seen wearing the same shoes and with a blood stain on his pants.

“You can clearly see the Defendant’s face and the blood stain on his pants,” court documents read.

Officers also found the knife that was believed to have been used to kill Calderon, as well as a second knife.

Prosecutors say recovered gloves with cuts in them also helped identify Williams. Officers said when they arrested him he had a cut on his hand. His mother told police she took him to the hospital to get stitches after the murder. She claims her son told her he cut his hand on a fence.

Officers also executed a search warrant of Williams’ residence where they say they found a pair of shoes matching those worn in the videos and a shoe box containing packaging for a knife of the same brand and model number as the knife found when officers canvassed the area of the Walgreens.

Police say Williams is suspected of robbing Calderon’s store four days before her killing, and also robbing another nearby Walgreens at North and Western avenues.

As CBS 2’s Charlie De Mar reported, court documents show Williams has a previous juvenile burglary charge and was cut loose from electronic monitoring not long before the killing.

The Cook County State’s Attorney’s office said it had no objection to his release from house arrest based on “specific information presented to the court.”

When we asked Chicago Police about Williams’ criminal history, there was only mention of the Walgreens robberies that occurred after he turned 18 – nothing on his juvenile burglary arrest.

“Sincere Williams turned 18 on July 4th,” said Chicago Police Area Five Cmdr. Eric Winstrom. “In a very limited time, we believe he committed three robberies, but as far as interaction with the Police Department that was documented, there is none.”

Williams’ public defender said the 18-year old suffered from schizophrenia.

The judge denied bail Wednesday.

CBS 2’s Steven Graves and Charlie De Mar contributed to this report.