Pawling's fingerprints were found on another envelope still in the evidence room, which was missing $1,640, officials said.
"A desperate man will engage in desperate conduct," District Attorney Thomas Hogan said in the release. "When the defendant fell into financial difficulties, he took care of his problems by stealing from his fellow officers, a charitable organization, and even the police evidence room."
Pawling, a 17-year veteran of the department when he retired in 2012, was charged in August with stealing from the Coatesville Police Benevolent Association while serving as its treasurer and from the Coatesville Police Athletic League while serving as its executive director.
On top of the new accusations that he stole from the evidence room, the District Attorney's Office on Wednesday charged Pawling, 43, with taking an additional $9,000 from those two groups.
Hogan said Pawling took nearly $2,800 from the athletic league to pave the driveway of his Walnut Street home. He is accused of purchasing with union money about $7,000 in computer equipment, iPods, ink cartridges, and school supplies at Staples, according to an affidavit released by Hogan.
On one check to Staples, Pawling is accused of forging the signature of former union president James Adudette, misspelling his name as Auddette, the affidavit said.
Pawling came under investigation in April when Coatesville detective Kevin Campbell, the incoming president of the police union, found discrepancies in the union's financial information.
According to a previous affidavit in the case, Pawling admitted in August in a recorded interview to stealing $30,000 to $40,000 from the union between 2009 and 2012.
Hogan has said union funds typically were spent on fees for officers' legal defense and on benefits for families of injured officers.
Coatesville Police Chief Jack Laufer said Wednesday that the department was "once again saddened" by Pawling's actions, calling his conduct a betrayal of the public's trust. Laufer took over the department - which has been plagued by lawsuits and staffing shortfalls in the past and spent much of 2012 without a chief - last January. Hogan said an audit on the evidence room, started after Laufer was hired, led to the discovery that money was missing from an envelope.
Hogan said the investigation remained open.
Pawling was previously charged with eight counts of forgery and 51 counts of theft, and was facing additional counts of fraud, theft, forgery, tampering with public records, and receiving stolen property.