Old Saybrook — Despite extensive searches, Coast Guard and other emergency personnel haven't located a teenager who went kayaking in Old Saybrook Monday or a man and woman who went boating in Groton Sunday.

The Coast Guard on Tuesday afternoon suspended its search for William Zadrozny, 18, whose overturned kayak was found Monday at 5 p.m.

"After working with our port partners to search extensively throughout the night and today, we've made the difficult decision to suspend the search," Cmdr. Andrew Ely, who is the chief of response for Coast Guard Sector Long Island Sound, said in a news release. "The decision to suspend is never made lightly, and our hearts go out to the family and friends of William Zadrozny."

Late Monday night the Coast Guard also suspended its search for Spencer Mugford, 20, and Sofia McKenna, 21, who left Groton on a boat owned by the University of Connecticut at Avery Point.

During a noontime news conference here, Capt. Keith Williams of the state Environmental Conservation Police said Zadrozny likely launched from North Cove, which is on the western side of the Connecticut River and shares a border with North Cove Road. Williams said officials found Zadrozny's car in a parking lot near the cove.

Ely said a self-locating data marker buoy helped officials develop a relatively small search area — it extends from Niantic Bay to the Clinton area.

Members of several departments helped with the search, which began after a good Samaritan found the overturned kayak. A life jacket and fishing gear were inside.

Searchers used boats, a helicopter and a plane.

Williams and Ely, saying they still were gathering information, declined to say where Zadrozny is from.

The men also addressed questions about the search for Mugford and McKenna.

Officials initially thought the pair were on a paddleboard but later learned it was the boat owned by UConn Avery Point.

They were last seen in a Snapchat post McKenna uploaded about 2 a.m. Sunday, when they were near New London Ledge Light. It isn't clear what time they began their trip.

Southold, N.Y., police officers found the blue-and-white sailboat, mastless, near Orient Point in Long Island Monday night. Authorities there said no one had walked up from the beach.

On Tuesday, UConn spokeswoman Stephanie Reitz said Mugford enrolled as a freshman on Aug. 28 last year. He was a student through April 20 this year, at which point he withdrew from the spring semester.

Reitz said McKenna is not listed as having attended UConn.

In an email sent to students and staff Tuesday afternoon, Annemarie Seifert, campus director of UConn Avery Point, said, "I want to make sure you know we are aware of and monitoring this distressing situation, and that our hearts and thoughts are with Spencer's family and friends."

"While Spencer is not currently a student, we know he has friends on campus and want to offer the Avery Point campus as a place of reflection and comfort," she said.

She said The Avery Point Office of Student Services is ready to help students, who can call (860) 405-9024 to make appointments or stop in during business hours. The Employee Assistance Program is available for faculty and staff, who can contact Gary Alger at gary.alger@uconn.edu or (860) 486-1307.

On Facebook, McKenna's mother, Michelle, described her daughter and Mugford as friends. She didn't say how they came to know each other.

During the conference, Ely said the decision to end the search was "challenging." He said the Coast Guard looks at the probability it will find an object or a person and considers factors related to survival, including water temperature.

Williams said the water temperature in the area was 56 degrees Tuesday morning and probably similar Monday afternoon.

"It's never easy to suspend a search," Ely said. "We treat every search like we're looking for our own."

Williams pointed out that state law requires boaters not only to have a personal flotation device on board but also to be wearing it until May 31.

"With temperatures like today, when it's close to 80, people feel comfortable," he said. They don't realize "what will happen when they hit water temperatures of 50 degrees. It takes a toll on the body very quickly."

Ely estimated the average person could last 20 hours in those conditions.

"Obviously this weekend has been a tragic weekend," Williams said. "But we're really trying to drive the message home: wear life jackets. It can save your life."

Williams said EnCon police handled five boating crashes from Greenwich to Stonington over the weekend. He and Ely said the crashes and simultaneous searches strained resources.

"I think that's one of the reasons that partnerships are key," Ely said. "Within this region and along the shoreline, the marine units work well together. We get together and plan exercises so we're prepared for events like this."

Day Staff Writers Charles T. Clark and Julia Bergman contributed to this report.

l.boyle@theday.com