Police are searching for the killer of a sixth grade teacher who was found dead inside her Lancaster city home Monday morning.

Nicole R. Mathewson, 32, taught at Brownstown Elementary School in the Conestoga Valley School District.

UPDATE: 16-year-old charged with killing elementary school teacher in the city

School officials became concerned when Mathewson failed to arrive at work Monday morning, police Chief Keith Sadler said Monday night.

A friend found her unresponsive in her home at 710 N. Franklin St. just after 9 a.m. and called 911.

Sadler said Mathewson had visible traumatic injuries and may have been stabbed. He said she likely was killed late Sunday or Monday morning.

An autopsy is set for 9 a.m. Tuesday.

Mathewson's vehicle, a black 2005 Mazda 3 sedan with Pennsylvania plate FVN-8421 is missing. Police issued an alert to surrounding law-enforcement agencies but the vehicle had not been spotted as of Monday night, according to Sadler.

According to newspaper records, Mathewson purchased the North Franklin Street home in 2012 and earned a master's degree in education from Eastern Mennonite University in 2013. She originally is from Owego, New York, according to her Facebook page.

The homicide occurred about two blocks from a McDonald's restaurant where two men were shot Saturday night. Sadler said the two crimes are not related.

"The only thing they have in common is location. There is nothing tying these two incidents together."

Sadler declined to say if there was evidence of forced entry or if police believe Mathewson was targeted. He said the scene was still being processed late Monday.

"Obviously, there are a lot of things that are still being looked at, a lot of information to examine," Sadler said. "What I can say is, in my more than 30 years of experience with these types of crimes, they're generally not random."

Sadler said he understood residents were uneasy and wanted answers, and said he's hopeful police will be able to release more information, possibly as soon as Tuesday.

Conestoga Valley Superintendent Gerald Huesken on Monday afternoon described Mathewson as a "wonderful, hands-on" teacher who was passionate about math.

He said she previously taught at the middle school and held a district-wide role as an elementary math specialist, but had worked at Brownstown for the last several years.

Her loss, he said, will be deeply felt.

"It's a relatively small school ... This will impact all staff and students and leave quite a void," Huesken said.

District officials met with staff after school Monday and shared with them what they knew, Huesken said.

An email was sent to parents, he added.

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Huesken said counselors will be available for students and staff at Brownstown Elementary and other district buildings Tuesday, and beyond if needed.

The district posted a statement about Mathewson's death on its website Monday.

In Mathewson's neighborhood, just north of McCaskey High School and consisting of mostly row homes, the killing left some neighbors on edge.

Jean Smith, 58, has lived on nearby Reynolds Avenue for 35 years.

She said she met Mathewson when the young woman moved in. The two talked about riding bikes together but never did, Smith said.

She described Mathewson as a "cheery girl."

"I'm in shock. It's so sad."

Tim Anderson, 28, moved to a home on Hamilton Street, about a block from Mathewson's home, two years ago.

Everyone on his block knows each other ... neighbors walk dogs and talk with each other, he said.

Anderson said the first year he lived there was quiet but said he's noticing an increase in crime.

He also said he's questioning if he should have a security system or some kind of self protection.

"I'd be curious to find out if this is a burglary-related crime," Anderson said of Mathewson's killing.

Mathewson's death is eerily similar to the 1992 murder of Christy Mirack, a teacher at Rohrerstown Elementary School.

Mirack, who also taught sixth grade, was found dead in her East Lampeter Township townhouse four days before Christmas.

Her body was discovered by the school's principal, who went to her home when she didn't arrive at school that morning.

Police said Mirack was beaten, strangled and sexually assaulted.

No one has ever been charged with her murder.

Police ask anyone with information about Mathewson's murder to contact them at 735-3300. Tipsters also may call Lancaster City/County Crime Stoppers at 1-800-322-1913 or anonymously text LANCS plus a message to 847411 (TIP411).

Staff Writer Ryan Mellon contributed to this report.