SAN FRANCISO -- Federal prosecutors have asked a judge to send former baseball slugger Barry Bonds to prison.

In court documents filed late Thursday, prosecutors objected to a recommendation by a federal probation officer that Bonds get only probation when he's sentenced for obstruction of justice Dec. 16.

In the documents, prosecutors asked that Bonds be sentenced to 15 months in prison.

Bonds, 47, was convicted in April of obstructing a grand jury's sports doping investigation with an evasive answer.

Prosecutors dropped three other counts charging Bonds with making false statements after the jury deadlocked on those charges. They accused Bonds of lying to the grand jury when he denied knowingly taking performance-enhancing drugs and said he allowed only doctors to inject him.

Federal sentencing guidelines for conviction on the obstruction charge recommend a prison sentence between 15 and 21 months. But Bonds' lawyers have cited an investigative report prepared by a federal probation officer for the judge that recommended a sentence of probation.

Defense lawyers said in a previous motion they disagreed, however, with the probation report's recommendation that Bonds spend an unspecified time under "location monitoring," a form of house arrest.

In their motion, Bonds' lawyers said the probation department cited Bonds' "significant history of charitable, civic and prior good works" as a major reason for leniency. The probation officer also noted that Bonds' conviction appears "to be an aberration when taken in context of his entire life," according to the lawyers.

The lawyers said the probation officer recommended probation because other sports figures convicted of similar charges stemming from the same sports doping investigation avoided prison.

Juries convicted cyclist Tammy Thomas of perjury for testifying she never used steroids and former track coach Trevor Graham for lying to investigators about his involvement with a steroids dealer. Both were sentenced to periods of house arrest, which is considered a form of probation.

Former professional football player Dana Stubblefield pleaded guilty to lying to investigators and was sentenced to probation.