BOSTON — In announcing a murder charge Thursday, Boston’s top prosecutor promised justice for the stabbing death of a 24-year-old “small-town girl” following her abduction last week in a city she came to love.

“Amy Lord was a small town girl, but she came to love Boston and it became the place that she called home,” Suffolk County District Attorney Daniel Conley said. “…We will not rest until justice is done in Amy’s horrible murder.”

Conley said Edwin Alemany, a man facing charges for allegedly attacking two other women last week in the same South Boston neighborhood, will face a murder charge in Lord’s death.

The 28-year-old Boston man, previously dubbed a “person of interest” in Lord’s killing, is undergoing a psychiatric evaluation at Bridgewater State Hospital after a judge found him unfit for an arraignment in connection with the other attacks. Police arrested Alemany on July 24 after he allegedly stabbed a woman, also charging him with punching a different woman on July 23.

Messages left for Alemany’s attorney, James Greenberg, weren’t immediately returned Thursday.

Police have said Lord was wearing gym clothes on the morning of July 23rd when someone kidnapped her and forced her to withdraw cash from five ATMs machines in less than an hour.

Her Jeep was found ablaze in South Boston about two hours later. A bicyclist discovered the body of the former high school cheerleader and native of Wilbraham, Mass., that afternoon in a park in the city’s Hyde Park section.

Lord was living in South Boston and working for a digital media company after graduating from Bentley University in 2011. While in college, she’d played intramural soccer and studied abroad in Spain. During her funeral this week, she was eulogized as someone who made friends wherever she went.

Authorities said Thursday that the homicide investigation reached a tipping point from a combination of forensic tests, witness statements and surveillance images. Police previously released images of Lord withdrawing money from the ATMs in a bid to find any witnesses who may have seen her with her killer.

Conley said prosecutors would present evidence to a grand jury, but wouldn’t publicly discuss the specifics of what police gathered.

On Thursday, authorities were searching the park where they recovered Lord’s remains and said their probe into what they called a complex case was ongoing. Boston Police Commissioner Ed Davis said the investigation “is not just a DNA case,” but involves circumstantial and other evidence.

The outbreak of violence unsettled South Boston residents and led police to step up patrols and hand out whistles to women as a safety measure. Davis was among law-enforcement officers and elected officials who met earlier this week with hundreds of residents at a community meeting to discuss public safety.

Conley said he spoke to Lord’s family Thursday before publicly announcing that Alemany would face a murder charge.

“They were relieved to learn of this development,” he said.

Police also have been investigating whether Alemany assaulted a woman in the city’s Roxbury section last September in a case that has led to the demotion of a Boston police detective since Lord’s homicide.

It came out after Alemany’s arrest last week that his ID was recovered at the scene of the 2012 attack, but police never arrested him. The police commissioner has said the detective on the case failed to do a thorough investigation.

Alemany is due in court Aug. 14.