BEAVERTON, Ore. (KATU) — A death investigation has been opened in Washington County after two bodies were found in an apartment in Beaverton on Wednesday.

The sheriff's office confirmed 45-year-old Nicholas Alexander shot and killed his 16-year-old daughter and then turned the gun on himself in an apparent murder-suicide. Alexander was an employee with the Oregon Department of Corrections.

Deputies were called on to perform a welfare check at the Baseline Woods Apartment complex located at 545 SW 291st Avenue just before 10 a.m. The caller told dispatch that they were concerned about one of the residents because they had not heard from them.

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Responding deputies entered the apartment and found Alexander and his daughter dead inside. Investigators did not say in what condition they found the deceased. The medical examiner will determine the exact causes of death.

The sheriff's office said Alexander was arrested for DUII around 3 a.m. Monday.

KATU spoke with a neighbor who saw deputies responding to a unit on the third floor of the complex.

"It's a very quiet area, tons of kids and families running around in here all summer long, kids all around. Never been no violence, no evidence for this to happen," the neighbor said.

The Hillsboro School District sent a letter home to families at the girl's school. According to the letter, the teen was a student at Century High School.

"I am writing this letter to share some very sad news. Yesterday afternoon, we learned that one of our students...died unexpectedly," wrote Principal Julie Kasper. "The Washington County Sheriff's Office is investigating this matter, so we are unable to share additional details at this time."

Click here to read the full letter that was sent home to families.

This case remains under investigation. Anyone with information is asked to call the sheriff’s office at 503-846-2500 and reference case number 50-24-18037.