BOULDER, Colo. -- Authorities released a sketch of the man who was stabbed and beaten to death in rural Boulder County Monday night, in the hope that someone will recognize him.

Sheriff's investigators also released a photo of a tattoo found on the man's ankle.

The man was found dead on the steps of a home after the rural homeowners called 911 to report he tried to force his way into the house with a knife.

Deputies said the masked man rang the doorbell of the couple's home just before 10:30 p.m. Monday and claimed to be a police officer. When 59-year-old Becci Starr answered the door, the man tried to force his way into the home with a water pistol, she said.

Starr screamed and tried to fight him off with a baseball bat, she said. The intruder then dropped the toy gun and took out a knife from his pocket and tried to attack her again, she said.

Starr's husband, 56-year-old Scott Mattes, said he heard her screams and ran down the stairs to her side. Mattes tackled the masked man outside the front door and struggled with him for a few minutes. Mattes eventually wrested the knife from the intruder and stabbed him in self-defense as Starr took the bat and struck the man again, the couple said.

Mattes tried to resuscitate the man after he was no longer deemed a threat, but he died at the scene, said sheriff's Lt. Phil West.

An autopsy showed the man died from stab wounds and blunt force trauma. His death was ruled a homicide by the county coroner.

The sheriff's office is still investigating the circumstances of the death and no decision on possible charges has been made.

The home where the man died is located in the 100 block of Poorman Road, off Sunshine Canyon, about three miles west of Boulder.

The man was described as a Caucasian male, possibly Hispanic, in his late 20s or early 30s. He had a muscular build, and was approximately 5 feet 10 inches tall and weighed 175 pounds. He had brown eyes and short, wavy brown hair.

The man had a scar under his chin and a series of irregularly shaped, non-surgical scars on his right thigh. The tattoo shown was on his right ankle and was red in color.

Anyone with information about the man's identity was asked to call Detective Steve Ainsworth at (303) 441-3627.