With her cousin dead and her boyfriend suspected of the shooting, a distraught Jayna Emerson, 17, of St. Paul, struggled to get out the words Monday.

"We know what happened; we know you're scared," she said in an appeal to boyfriend Alfredo Gutierrez-Gonzales, 19. "Please turn yourself in so we know you're OK and we can see you."

The public plea came in front of the West Side house where Jacob MacKenzie, 15, a quiet, well-liked 10th-grader, was shot to death early Sunday, leaving not just his family, but his teachers at nearby Guadalupe Alternative Programs, to mourn him.

As for the suspect, known to friends as Freddy, Emerson described him as a "great boyfriend" determined to "turn his life around."

Earlier this year, Gutierrez-Gonzales pleaded guilty to terroristic threats in connection with a MySpace message in which he bragged of owning an AK47 assault rifle and an Ingram Mac 11 assault pistol, and also had claimed membership in the Brown Pride street gang, according to Hennepin County District Court records.

The message, sent to a man then dating a woman identified only with the initials "J.E.," cautioned the recipient to watch his back, and to keep a close eye on his stepdaughter, too, "cuz it hurts when someone you love goes missing," the MySpace message said.

Police spokesman Peter Panos said Gutierrez-Gonzales also had a juvenile criminal record in Ramsey County, but he had no details. Police still are trying to determine, Panos said, what led to Sunday's shooting, which occurred about 12:25 a.m. and left MacKenzie dead on the family's front porch.

"As far as [if it was] an argument or if it was just an accident -- we just don't know," Panos said. "That's why we need to talk to Freddy. We need to hear his side of the story."

Speaking outside the home Monday, too, was the victim's mother, Michelle Olson.

"I want my son back," she said. "And I'll never have him back ... he got taken from me."

Weapon found

The house on the 500 block of Concord Street is home to three generations of family members, including MacKenzie and Olson, and Emerson and her mother, Karen Emerson. About 10 people were inside the house at the time of the shooting, but only a few people witnessed it, Panos said.

Police recovered a small semi-automatic rifle believed to be connected to the shooting about six blocks away in a wooded area near state Hwy. 52, Panos said.

Of the relationship between the victim and suspect, he said: "They were acquaintances -- and friends, to a point."

MacKenzie is the second student at Guadalupe Alternative Programs, a West Side alternative school, to be killed by gunfire this year, associate director Jody Nelson said Monday. Staff and students spoke of MacKenzie on Monday at an all-school meeting and, later, in a smaller "talking circle," she said.

Staff members who work with ninth- and 10th-grade students were crying, Nelson added, and the students noticed, making a point of "checking up on them through the entire day."

Eight boys worked in an art room to prepare a poster in MacKenzie's memory.

"The circle of life and death," Nelson said, "really becomes [part of] the curriculum."

Anyone with information about the shooting -- and the whereabouts of Gutierrez-Gonzales -- is asked to call police at 651-291-1111.

Staff writers Rochelle Olson and Lora Pabst contributed to this report. Anthony Lonetree • 651-298-1545