AUSTIN — Officials at the University of Texas at Austin are stepping up security and urging students to be more careful after determining that a body found on campus this week belonged to an 18-year-old dance student who was walking home.

Haruka Weiser, a freshman from Portland, Ore., left the university’s drama building around 9:30 p.m. Sunday, police said, telling a friend she was heading to her dorm. She never arrived, and her roommates reported her missing around 11:30 the next morning.

Her body was found on campus Tuesday in Waller Creek by the university’s alumni center, a short walk from the drama building.

Police and campus authorities have released few details, saying they were being intentionally vague to protect the integrity of the investigation. But on Thursday, Austin police released a surveillance video of a man they consider a suspect in Weiser’s murder. He was seen near the football stadium’s north side walking as he straddled a red or pink woman’s bike. Police said he was videotaped in the area, which appears well lit in the video, for an hour or so. There’s hardly any foot traffic in the video, although an occasional car or bicyclist passes by.

“At this time, we do not know the identity of the suspect and we will definitely need the support of the community,” said Troy Gay, an assistant chief at the Austin Police Department. “We would like the students and the faculty to have a high degree of vigilance until our suspect is arrested.”

University President Greg Fenves said he has asked the Texas Department of Public Safety to conduct a comprehensive security review, and university police and outside law enforcement agencies have stepped up patrols of the university grounds.

“To our students: You expect and deserve to be safe,” Fenves said at a news conference at the UT Tower on Thursday.

The UT-Austin campus is in the middle of a large urban area, but is generally safe. According to federal crime statistics, Weiser’s death is the first homicide on the campus in this century.

But the manner of her death is chilling to students and other members of the campus community. University and law enforcement officials have repeatedly warned students to be careful on campus and be aware of their surroundings. Students should walk in groups, especially at night, officials said. And they should stay vigilant and think twice about focusing on their phones or wearing headphones.

The university police department has officers working 12-hour shifts to increase foot and bicycle patrols, and the state has lent 20 troopers, including officers on horses, to assist.

DPS will also review the security cameras, outdoor lighting, building security and other aspects that could affect student safety. Fenves said he is prepared to take concrete steps to implement any recommendations.

That has helped ease the worry of some students and parents, but many say they will remain spooked until someone is caught.

“It’s been pretty uneasy,” said Elizabeth Garcia, a junior biology major. “Everyone is kind of freaking out because this happened on our campus.”

“The unthinkable brutality against Haruka is an attack on our entire family,” campus President Greg Fenves said in a letter to the campus community Thursday. “Law enforcement is fully engaged to do everything to bring the perpetrator who committed this crime to justice.” Fenves asked the Austin Police Department to take the lead in the investigation. The Texas Department of Public Safety and Texas Rangers are also involved in the case.

In the meantime, the campus is in mourning.

University officials announced a community gathering in Weiser’s honor at 5:30 p.m. Thursday, and counseling services and support for students.

At the press conference, Fenves read a letter from Weiser’s family. It expressed sadness and a request for privacy, but also hope that her death would bring changes that make the university safer.

“If her death can somehow make it safer to walk home, if it will prevent another assault or murder, then at least we can find some sense behind an otherwise senseless murder or death,” Fenves read.

Correction: An earlier version of this article incorrectly reported the day Weiser was last seen. The article has been updated.

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