HOCKESSIN, Del. (WPVI) -- A man described as having an "obsession" with a Delaware psychiatrist has been arrested and charged with her brutal murder inside her Hockessin home.Twenty-one-year-old Christopher Frick, of Newark, is charged with first-degree murder and is being held without bail in the death of 55-year-old Caroline Ekong.While announcing the charges on Thursday, investigators said Frick was fixated on the doctor."This is a very, very tragic case where someone was obviously obsessed with another individual," said Colonel E. M. Setting of the New Castle County Police.Police said three years ago something happened - they won't disclose exactly what - and the two met. They've had no interaction since, but during that time Frick became fixated on the psychiatrist and plotted to kill her, police said. She had no idea.Investigators allegedly found numerous documents giving them insight into the extent of Frick's obsession with the psychiatrist. Police said no one else in his life seemed to have any idea of his fixation - not even his parents, who are cooperating with police."There was no indication that this was going to happen. There was no communication that anything like this was going to occur," said Sgt. Gustavo Zeissing.In an online review of the Rockford Center, where Ekong worked, Christopher Frick complained about his treatment there. He wrote, "The person who imprisoned me was Caroline Ekong whose ego is so large that she would never be able to admit that she was wrong."Edwina Bell said she worked with Ekong as a mental health advocate."Just a person who believed in what she did and never ever gave up on the people she served," said Bell.Frick was a senior mathematics major at the University of Delaware up until his arrest on Wednesday.The killing happened early Wednesday morning inside Ekong's home in the unit block of Withers Way in the community of Sanford Ridge.Police said Frick parked his vehicle in a lot near Ekong's home, then broke in and confronted her. There was an altercation, police said, then Frick stabbed Ekong multiple times."His intention was to commit homicide," said Det. Sgt. Gus Issac.Ekong's body was found by her daughter around 4 a.m.About a half hour later, police said they received a call from Frick, who allegedly said he was responsible for the woman's death.New Castle County Police Officer Tom Jackson explains, "Within about a half an hour, about 4:27 a.m., we received a call from the subject giving us information that he was responsible for this incident."Patrol units went to a home on Springbrook Lane in the Autumnwood development and took him into custody without incident. Police said he provided details that indicated his involvement."We are not looking for any other suspects at this time," said Officer Jackson.The Rockford Center issued a statement that reads in part: "The Rockford Center is cooperating with local authorities and will continue to do so. On behalf of all the staff at the Rockford Center, I extend our thoughts and prayers to the family during this extremely difficult time."