The psychiatrist who treated James Holmes before he opened fire in a Colorado cinema, killing 12 people and wounded 58 others, has said she would have called police and had him detained if she had known his plans.

A prosecutor says James Holmes considered other locations and methods for his attack, including biological warfare, before deciding on a mass shooting at a suburban Denver movie theatre.

Prosecutors said they will seek the death penalty against the man accused in last year’s cinema attack that killed 12, wounded 70, and spurred new gun control laws in Colorado.

Prosecutors have rejected the plea offer of the man accused of gunning down 12 people in a Colorado movie theatre last July, saying his defence team’s offer of a guilty plea in exchange for avoiding the death penalty was not legitimate.

Prosecutors say they are not ready to accept the offer of a guilty plea from the Colorado cinema shooting suspect in exchange for avoiding the death penalty.