SAN JOSE -- The mysterious monthlong disappearance of a senior who neighbors referred to as "The Magician" ended tragically on Thursday, when family members found Stanley Jacobson stabbed to death in his modest apartment.

Jacobson, 69, was found in his home at the Hilltop Manor Senior Apartments on Ironwood Drive about 11:30 a.m., and was pronounced dead at the scene. He was the city's eighth homicide of 2013, and the second stabbing death reported in two days.

San Jose police spokesman Sgt. Jason Dwyer said they made an arrest in the case but did not release the suspect's identity.

"We are confident that this suspect is responsible for the crime," Dwyer said. "We are not looking for other suspects, and it's not something that the public has to worry about."

After Jacobson was reported missing on Feb. 18, police put out an appeal to the public in an effort to help find him as he was considered at-risk with the onset of dementia, and had last been seen on Feb. 5. They were also looking for a woman named Regina Butler who detectives believed might be with him.

"The original fear was that somehow Mr. Jacobson would be exploited financially or otherwise," Dwyer said.

While Dwyer would not say whether Butler was the suspect they had in custody, he confirmed they located her and a neighbor said he saw her outside Jacobson's apartment earlier Thursday, not long before his body was found.

"I asked her, 'What are you doing here?'" said Benjamin Ramos, 85. "I wanted to see if she knew anything about Stanley. I said, 'You were the last one to see him, you were the only one with an extra key for his car.'"

As he spoke to her, Ramos said, Butler acted erratically and began to cry.

Another neighbor, Michael Christian, said Jacobson was very friendly but began keeping to himself when he started dating Butler, who was frequently at his apartment.

"He would bring her in late at night and became very unsocial," he said. "He never introduced her to us."

Jacobson left behind his wallet and identification when he disappeared, but Christian -- who checked on his apartment frequently in the past month -- said he did take his deck of cards.

Cards, coins, handkerchiefs and handcuffs -- they were the tools employed by Jacobson to entertain his friends in a variety of stage and escape acts.

"He was a great, friendly guy," said Christian. "He would do his little magician tricks and everybody would just laugh. This is just a shock."

What remains unknown is where Jacobson was for the past month. Police said he could have been killed days ago, but neighbors said people have been checking on his apartment and believed it was unlikely that a body could have gone undetected for long.

His neighbors said that while he may have had the onset of dementia, Jacobson's mind remained sharp.

"He had a good memory, would talk about movies and songs," Ramos said. "Very friendly, and very conservative. Everybody liked him; he didn't take drugs or drink, only smoked."

But it was clear, Ramos said, that Jacobson had strong feelings for Butler.

"He was the person to hand her money," Ramos said. "It's one of those things; he was in love with her."

Contact Eric Kurhi at 408-920-5852. Follow him at Twitter.com/erickurhi.