2 killed, 1 critically hurt in series of stabbings in college town

The FBI is helping investigate three "brazen" stabbings -- two of which killed a college senior and a homeless man -- within one week in Davis, California, according to police.

Davis Police Chief Darren Pytel said Tuesday that authorities are still investigating whether the "unprecedented" stabbings are related, though he noted that the suspect descriptions for the second and third attacks are "substantially similar." There were no witnesses to the first attack.

"We aren't able yet to positively link the three crimes," the chief said. "We're still waiting for evidence to come back."

The most recent stabbing took place at about 11:45 p.m. Monday at a transient camp in Davis, about 15 miles west of Sacramento. A woman said she was stabbed multiple times through her tent, police said. The victim underwent surgery and is in "critical but stable condition," Pytel said.

She "was able to provide a description of the assailant and she was able to tell us what happened," the chief said.

The suspect is described as a college-aged man with a light complexion and curly hair, police said. He's thin and stands at 5-foot-6 to 5-foot-9, police said, and was last seen wearing black Adidas pants with a white stripe on the side and carrying a brown backpack, police said.

UC Davis said it issued "a campus WarnMe message" around 1 a.m. Tuesday. The city initiated a "shelter in place" order overnight that was lifted several hours later.

Just days earlier, around 9:15 p.m. Saturday, UC Davis senior Karim Abou Najm, a 20-year-old computer science major, was stabbed to death at Davis' Sycamore Park, according to the university and police.

"Karim was a wonder of energy, a free spirit, someone who just wants to see goodness around him," his father, Majdi Abou Najm, told Sacramento ABC affiliate KXTV.

"I am simply devastated," UC Davis Chancellor Gary May tweeted. "By all accounts, he was an exceptional student, son and friend."

May added, "I know many of you are frightened by what's happened, especially so quickly after the stabbing incident that occurred on Thursday in Davis' Central Park."

On Thursday, David Breaux, a homeless man who was a staple in Davis for over a decade, was stabbed multiple times and killed in the city's Central Park, according to police. He was found on a park bench where he often slept, Pytel said.

Breaux dedicated his life to compassion and restorative justice, and was a beloved presence in Davis, friends said at a vigil this weekend. The Davis community had worked together to build a bench, dubbed The Compassion Bench, for Breaux to have a place to sit and talk with Davis residents about what compassion meant to them, mourners said. Breaux kept notes and turned those conversations into a book, they said.

Breaux's family said in a statement, "David was an extraordinary and beloved brother, community member, and human being. He simply existed on a higher plane than most of us. If there's anything positive that can possibly come from this, I hope it's that we all find it in our hearts to live more compassionately, which is exactly what he would've wanted."

The chancellor said in his statement, "Like so many of you, I am grieving the death of David Henry Breaux, known as the 'Compassion Guy.' ... David led a life with real purpose, to connecting humanity for the greater good, something we should all aspire to do."

As the investigation continues, UC Davis announced a series of security measures, including moving evening classes from in-person to online; ramping up officer patrols; and increasing the hours available for safe rides from campus to off-campus locations.

Police said in a statement, "If you must be out at night, consider traveling in groups, and report suspicious activity to the Davis Police Department by calling 530-747-5400, emailing policeweb@cityofdavis.org, or if you would like to remain anonymous, call our tip line at 530-747-5460."

ABC News' Dea Athon, Alyssa Gregory and Jenna Harrison contributed to this report.