Juan Manuel Alvarez exhibited bizarre and delusional behavior for at least five years before causing a deadly Metrolink crash three years ago, his wife testified Tuesday.

Carmelita Alvarez said her husband -- who is on trial for murder -- was extremely possessive of her and often accused her of having affairs, even with her own nephew. He also tried to kill himself three times, she said during two days of testimony that began Monday.

"I had to be in the middle of the bed facing him. He had to be holding my hand, because he thought if I turned over, somebody else was there," Carmelita Alvarez said as she wept. "He thought I had cameras on the mirrors in my closet. He would say, 'Why are you recording me?' "

She said her husband believed that the television "was talking to him," and he was convinced that she and their children were plotting against him behind his back.

"As you sit here today, do you think there is something mentally wrong with Juan Alvarez?" defense attorney Thomas W. Kielty asked her.

"Yes, I do," she responded.

Defense attorneys said Carmelita Alvarez's testimony supports their position that their client was a mentally ill man addicted to drugs who unintentionally derailed the train during an aborted suicide. The wreck left 11 passengers dead and wounded 180 others.

Prosecutors, however, sought to use Carmelita Alvarez's testimony to paint a very different picture of the defendant. They said he willfully set out to cause the worst train wreck in Metrolink history because it would be a sure way to get his wife's attention.

Carmelita Alvarez testified that her husband never seemed committed to getting help for his drug habit or mental illness. She acknowledged that she would always show him affection and pity after his suicide attempts.

"He didn't want to get help," said prosecutor Cathryn Brougham. "He wanted to come home to you, right?"

"Yes," the defendant's wife replied.

Carmelita Alvarez also acknowledged that she filed for a restraining order against her husband in 2004, claiming that he had "threatened to do anything if I don't let him see our kids." She said she withdrew the request after the train catastrophe and started to visit her husband in jail because she felt guilty.

"I feel responsible that I couldn't help him. I couldn't find him the help that he needed," Carmelita Alvarez said fighting back tears. "I don't feel responsible for what he did."

ann.simmons@latimes.com