She was upbeat, friendly, always armed with a smile. Since going missing Tuesday afternoon, Annie Le GRD ’13 has been sorely missed by all who knew her.

Following the discovery of a female body presumed to be Le in the building at 10 Amistad St. on Sunday evening — the same day Le was to wed her college sweetheart — friends, family and colleagues are mourning her loss.

Described as sweet, spunky and smart, the 24-year-old pharmacology student and Placerville, Calif., native was scheduled to be married Sunday to Jonathan Widawsky, a graduate student at Columbia University whom she met at the University of Rochester.

While working overtime in her Yale laboratory in the weeks leading up to her wedding, Le chatted constantly about her excitement for the ceremony, colleagues said.

“Lucky I’m in love with my best friend :),” Le had written on her Facebook profile. According to status updates and wall posts on the profile, Le and Widawsky were engaged in July of 2008 and celebrated their five-year anniversary as a couple in March of this year.

At Yale, colleagues at Le’s lab said she was dedicated to her research. Recently she had decided on the topic of her dissertation: the study of how certain proteins are involved with metabolic diseases such as diabetes.

Associate professor of pharmacology Anton Bennett, Le’s faculty adviser, said Le — who received a National Science Foundation grant in 2008 — had “tremendous potential.”

“I can tell you that we are fond of all our graduate students, and among them Annie was a bright spot,” pharmacology professor Gary Rudnick wrote in an e-mail message Sunday night. “She almost always had a smile when I saw her in the hallways. … This is a very tough loss for all of us in the department.”

Le made an impact not only on those around her at Yale but also on colleagues at the National Institutes of Health, where she participated in a scholarship program during two summers as an undergraduate.

Jennifer Simpson, a fellow NIH scholar who last spoke with Le about four weeks ago, recalled how on one summer night during the program, Le burst into her room with a hankering for Vietnamese food. Traveling on the subway from Bethesda, Md., to a Vietnamese restaurant in Virginia, the two went on a spontaneous “adventure” inspired by Le’s craving. “I thought you’d like it,” Simpson remembers Le saying.

“Annie enjoyed sharing her life with people,” Simpson said late Sunday night. “She wasn’t a loner. She was alive. She had a vibrant personality. She wanted to be there with people.”

At Union Mine High School in El Dorado, Calif., Le was valedictorian and a member of the National Honor Society and the culture club.

Though small in stature, Le stood out among her classmates and was not afraid to speak up for herself. “She was a spunky little thing,” high school friend Cierra Montes said Sunday night.

Shaun Perisho, another one of Le’s classmates, recalled how substitute teachers would often mispronounce Le’s surname (which is pronounced “lay,” not “lee”), one of Le’s pet peeves. But on such occasions, the usually vocal student would hold her tongue out of respect for the teacher, instead glancing back at her classmates with a wry grin.

Le also spent time in high school volunteering at the Marshall Medical Center in Placerville.

Classmate Tiffany Filice described the close relationship Le developed with Filice’s grandmother, who was a patient at the Marshall hospital. Le logged extra hours visiting the woman, who gave Le a graduation gift in appreciation.

Pursuing her passion for science at the University of Rochester, Le received a bachelor of science in cell and developmental biology in 2007. She graduated cum laude with awards for her achievements in biology and her leadership on campus, a spokeswoman for the university said.

But despite her heavy academic workload at Rochester, Le always found time for her friends, who called her energetic and “the happiest girl you’d ever know,” as college friend Mark Biery said in a phone interview around noon Sunday. “She would work those crazy hours, but she would still take time out of her day to come see us, or we would come see her.”

As fellow NIH scholar Michael Torres put it in a phone interview Sunday afternoon: “She’d be the last person that anyone would ever want to see harmed, and that’s, I guess, why it’s so shocking.”

Martine Powers and Victor Zapana contributed reporting.