ATTLEBORO -- For the first time in recent memory, the Attleboro police union has endorsed a candidate for Bristol County district attorney, throwing its support behind Fall River lawyer Sam Sutter.

Two union members, President Russell Castro and a past president, Detective Tim Cook Sr., both detectives, said Thursday the union supports Sutter because he promises better cooperation and leadership.

Cook took a swipe at District Attorney Paul Walsh Jr. for what he said were lenient plea bargains in several local cases, calling the agreements `` Cinderella deals.''

The Attleboro announcement marks the third police union in Bristol County to support Sutter in his race against Walsh.

Walsh said in a later interview that he was untroubled by the endorsements Sutter is racking up, asserting voters today are sophisticated enough to make up their own minds. During a press conference outside the police station with Sutter by his side, Castro said, `` it is time for a change in leadership of the Bristol County district attorney's office.''

More than half of the 75-member union turned out for a vote at a union meeting last week and declared support for Sutter, Castro said. The vote was unanimous.

Castro praised Sutter's experience as a former prosecutor and private attorney.

`` Your integrity, fairness and vision will restore commitment, energy and focus back in the office of Bristol County district attorney,'' Castro said of Sutter.

Sutter, an assistant district attorney in Walsh's office for seven years during the 1990s, including two years as supervising prosecutor in Attleboro District Court, is trying to unseat Walsh in the Sept. 19 Democratic primary.

Because there is no declared Republican candidate, the winner of the primary will likely be district attorney.

Walsh has held the office for 16 years.

The Attleboro Police Association is the third police union to line up behind Sutter.

Westport police endorsed Sutter earlier this week and New Bedford police endorsed Sutter last week.

When asked about the risks of entering the political fray for the office of the county's top law enforcement officer, Castro said that even if Sutter does not prevail, Walsh will `` still get the message'' about police lacking confidence in him. `` That's how strongly we feel about this,'' Cook added.

Saying he would restore the partnership between police and the district attorney's office, Sutter said police under Walsh's leadership are shunted aside and their concerns ignored.

`` They are being told to `Go to the sidelines. We will call you when we need you.' I will stand shoulder-to-shoulder with police marching down the field,'' Sutter said.

Sutter said he will hire more assistant district attorneys and criticized Walsh for two hires, including a Fall River city councilor, to staff `` community outreach'' positions.

Sutter also said politics plays a role in Walsh's office, which he said results in inconsistent sentences and `` what I call justice by connection, not conviction.''

He renewed criticism that Walsh has not aggressively pursued court-ordered wire taps against criminals, and said gang activity has grown in Bristol County under Walsh's watch.

When asked about the police union endorsements, Walsh said he has not sought endorsements from police unions.

Walsh said he avoids `` mixing politics'' with law enforcement and with those `` you have to work in court everyday with.''

He said the endorsements have little value because `` in this day and age, people make up their own minds on who to vote for.''

Concerning Sutter's criticisms about gang activity and wire taps, Walsh said wire taps are `` 1980s technology'' in an age of wireless phones. Walsh said he uses pin numbers, `` trap and trace'' and other methods.

He said gang activity has increased across the state and is a nationwide problem.

`` Blaming one district attorney for a nationwide problem is an attempt to mislead the public about the nature of the problem,'' he said.

During the press conference, Cook took Walsh to task for what he said were lenient plea bargains in a number of local cases.

He read a letter to Walsh from now retired Attleboro Detective Lt. Kenneth Collins asking why attempted murder charges were reduced in a South Main Street shooting and a domestic violence case in which a man tampered with the brake lines of his ex-girlfriend's car.

Cook said no one from Walsh's office responded to the letter, but Walsh said an assistant district attorney spoke to Collins about the shooting case.

In the domestic violence case, Walsh said the ex-girlfriend twice failed to appear in court, and declined to testify.

Cook also criticized Walsh's handling of a 2003 child pornography case in which he said the defendant received no additional jail time.

Walsh said one of his prosecutors recommended a 4- to 5-year prison term when the defendant pleaded guilty last year, but the judge gave the defendant time served, which was about one year.

Cook also said police departments are now required to document their confidential informants for the district office when they are seeking leniency for them in criminal cases.

But Walsh said the policy was instituted when prosecutors were led to believe that people who were supposed to be police informants were never working on behalf of police.

`` The reason for the policy is that when we receive a request for leniency, we need to know why,'' Walsh said.

Walsh said documentation about informants is kept confidential by his office and the policy has not affected the ability of police to use informants.

`` To my knowledge, no informant has ever been harmed or threatened as a result of the policy,'' Walsh said.