PITTSBURGH — Pittsburgh saw more murders and fewer of them solved last year than in any of the previous five years.

Records obtained by the a Pittsburgh newspaper show the city’s police department investigated 71 homicides in 2014 as of Tuesday compared with 46 homicides in 2013.

The newspaper reports police made arrests in 28 cases for a 39 percent clearance rate.

In 2013 the clearance rate was 63 percent.

Allegheny County District Attorney Stephen A. Zappala Jr. said as much as 80 percent of the violence can be attributed to drug trade.

Zappala said criminals are becoming more sophisticated in covering up evidence, making the job of solving crimes more complex.

He said grand juries who meet behind closed doors are being used to protect witnesses who fear retaliation.