A Missouri death row inmate has asked the state Supreme Court for a new trial.

Lawyers for 54-year-old John Middleton have submitted court filings in which they introduce new evidence that they say warrants him getting a new trial for one of his three murder convictions.

That conviction for the 1995 fatal shooting of Alfred Pinegar was considered an aggravating factor that justified the death sentences he received for the two subsequent convictions.

Among other things, the lawyers argue that some investigators whose questionable conduct led to the recent overturning of another capitol case also mishandled Middleton's cases.

They also submitted sworn testimony from a new witness who says he was beaten by two fellow drug dealers who suggested they killed Pinegar.

The state dismisses the validity of the claims.