A Pinellas County teacher who fatally shot his ex-wife, their two children, another woman and himself in December left behind a letter that indicated the killings would cleanse the world of "sociopathic" and "unethical" tendencies, according to newly released documents.

"Though this act may be viewed as depraved and evil, it does, in fact, leave the world a better place," authorities said Oliver Thomas Bernsdorff wrote in a letter found on his computer after the slayings.

Ballistics tests confirm Bernsdorff used the same gun in all the killings and to take his own life when state troopers tried to pull him over for driving erratically, Clearwater police spokeswoman Elizabeth Daly-Watts wrote in a statement.

In the letter released by authorities, Bernsdorff describes himself and his ex-wife, Jennifer Renee Davis, 27, as sociopaths, and writes their children are likely to turn out the same.

Given their genes and the "trauma" of the couple's separation, Bernsdorff wrote, "it is in the best interest of society and follows natural law that the aberrations, Jennifer, the progeny, and myself included, be eliminated." He also targets Andrea Pisanello, writing that she is "an unethical and salacious human being" and should also be killed.

Records show Bernsdorff was mired in debt in the months before the killings. Daly-Watts said detectives did not find any records indicating Bernsdorff had a history of mental illness.

Police found the bodies of his ex-wife and her roommate, Andrea Pisanello, 53, early Dec. 14. Authorities later found the bodies of the couple's two children, Oliviana, 4, and Magnus, 2, shot in their beds.

The investigation did not indicate in what sequence the women and children were killed.