An Ellicott City teenager died of poisoning early yesterday morning, five days after drinking a Vanilla Coke that police say a longtime friend spiked with cyanide.

Howard County police have altered charges against that friend, Ryan T. Furlough, 18, a senior at Centennial High School, to include first-degree murder. If convicted, he faces a life sentence without parole.

Benjamin Vassiliev, 17, a junior at Centennial, had been in critical condition at Johns Hopkins Medical Center since Friday night. Police said he grew ill after he went to Furlough's house in the 3500 block of Rhode Valley Terrace after school that day. The two teenagers were alone in Furlough's basement playing video games when Vassiliev began having seizures about 8 p.m., police said. One of Furlough's parents was home and called 911.

"We have been hoping and praying for the recovery" of Vassiliev, Furlough's parents, Susan and Tom Furlough, said last night. "We are so sorry for the pain and suffering our son has caused. Our heart goes out to all those involved."

The Vassiliev family, in its own statement, thanked the community for an "outpouring of support."

Furlough was arrested Sunday morning and charged with attempted first-degree murder and first- and second-degree assault. According to court documents, Furlough said that he had been thinking about killing Vassiliev since October, possibly over a mutual love interest.

During a search of Vassiliev's house, police found a letter from Furlough dated June 19 that mentioned Vassiliev's girlfriend, documents show. "There isn't a day that passes by where I don't think about her," Furlough wrote. "I want to tell you this as I did with her, I will never give up until I have the key to her heart."

Furlough ordered the poison over the Internet using his mother's credit card, police said. Investigators said they found a package and shipping papers for potassium cyanide at Furlough's house. Police impounded computer records that they said link him to the purchase from a Louisville chemical supply company.

Furlough's lawyer, Jan O'Connor, did not return several phone calls yesterday. But in an interview Monday, she said Furlough had suffered from depression and has been in counseling for months.

O'Connor said that Furlough was under a suicide watch at the Howard County Detention Center and that she asked the County District Court on Monday to order him moved to a psychiatric facility "to determine his competence and what, if any, treatment he needs."

Yesterday, Furlough remained at the detention center.

At Centennial High School, where a crisis team has been on duty, students said that the three -- Furlough, Vassiliev and his girlfriend -- all seemed to be good friends and were often seen hanging out, walking down the halls and hugging one another.

Lawrence Schaub, a neighbor of the Vassiliev family on Joycin Court in Ellicott City, said that the family was well-liked and that Vassiliev was popular, often getting rides home from friends' parents. The teenager was a familiar presence on the block, he said.

"I would see him out playing, riding his skateboard after school," Schaub said. "I've never heard anybody say anything negative about that family."

Yesterday morning, as Schaub was going to work, he saw Vassiliev's stepfather walking into the family's townhouse, which was still covered in Christmas lights. Schaub asked him how Benjamin was doing, and the stepfather told him that they had taken the teenager off life support the night before.

"He was devastated," Schaub said.

School officials described Furlough as a computer enthusiast and Vassiliev as a gifted actor, who played a lead role in a recent production of "A Midsummer Night's Dream." A Vassiliev family spokesman said last night that the family was not ready to speak publicly and is making funeral arrangements.

Staff writer Christian Davenport contributed to this report.

The charges against Ryan T. Furlough, 18, now include first-degree murder. Benjamin Vassiliev, 17, had been in critical condition at Johns Hopkins Medical Center since Friday night.