A father and son who are key witnesses against the Stockton man suspected of shooting a California Highway Patrol officer to death during a traffic stop two years ago could have some big credibility issues if they take the witness stand this spring.

The father, rap-music producer Christopher Hicks of Stockton, destroyed the alibi of defendant Columbus Allen when he testified during a grand jury hearing seven months ago, but prosecutors never asked about the drugs and weapons found in Hicks' home, something a defense attorney surely would point out.

And a son who backed up his dad, 17-year-old Dujuane Hicks, was recently arrested and charged with murder in San Joaquin County.

"One question I'm going to ask is, 'Mr. Hicks, where's your son?' " said defense attorney Ramon Magaña, predicting a likely scene when Allen goes to trial in March.

A crucial piece of evidence against Allen could be called into question, too, according to legal papers the defense filed in Stanislaus County Supe- rior Court. The papers will be the subject of debate Monday morning.

When the body of officer Earl Scott was found about 4:40 a.m. on Feb. 17, 2006, the officer was gripping registration papers from a 1990 Nissan Maxima owned by Allen's wife.

According to a transcript of a three-day grand jury proceeding that was held behind closed doors in June, prosecutors believe cell phone records place Allen in the vicinity when Scott was shot and killed, according to a transcript of that hearing.

But the defense contends that an initial check of Allen's cell phone turned up empty, failing to place him on the highway or in the vicinity at the time of the fatal shooting, it was asserted in legal papers.

And though the registration papers led the authorities to Allen, Scott had identification cards from three other people in his pocket, as well.

Magaña has asked for more information about each of these facts, and a whole lot more, in a discovery motion filed with the court. He says he needs more information so he can build a defense for Allen, 32, who is charged with first-degree murder and could be sentenced to death if convicted.

In response, the district attorney's office filed legal papers saying much of what the defense is seeking has been conveyed already or is out of bounds. Deputy District Attorney Alan Cassidy declined to comment.

The dispute is a routine matter in criminal trials: Prosecutors must turn investigative reports over to the defense, defense attorneys frequently complain that they cannot effectively represent their clients, because the authorities are hiding the ball, and judges settle the matter.

When they presented their case to the grand jury, prosecutors argued that Allen shot and killed Scott because Allen was driving on a suspended license and had a gun with him. As a felon who had been convicted of transporting cocaine in 1998 and auto theft in 1999, the possession of a weapon was enough to send Allen back to prison.

Allen told authorities that he was at Hicks' home on the evening before the shooting and stayed all night. Hicks and his son said Allen showed up about 6 a.m., cleaned mud off his shoes and asked Dujuane Hicks if he would trade jackets, a request the younger Hicks declined.

Magaña's laundry list of requests, which includes questions about the protocols used when authorities concluded that Allen had gunshot residue on his hands and sweat shirt hours after Scott was shot and killed, sheds new light on the high profile case.

Here are a few examples:

THE GAP -- Defense attorneys want to know what Scott was doing during the 40 minutes preceding his death, arguing that dispatch logs have a gap that authorities have yet to explain. They also want records for Scott's cell phone, in case the officer was communicating by phone rather than radio. The prosecutor said there is no unexplained gap, adding that officers frequently patrol for substantial periods of time without calling dispatch operators. Authorities have no cell phone records to share, the prosecutor said, because they gathered Scott's cell phone number and nothing more.

SEARCH WARRANT -- Allen's lawyers also allege that investigators entered Allen's former home on Jill Circle in Stockton before a judge signed a warrant, something that could lead to the suppression of evidence if items or information was obtained in an illegal search. The defense argues that some dispatch logs are missing, perhaps even tampered with, while the prosecutor counters that the logs have been turned over.

VIDEO -- The defense attorney wants video footage from the Ripon Police Department, which has a camera posted along Highway 99. Such images could corroborate or refute the accounts of a passing motorist who said he heard a popping sound, saw the officer drop and saw a small dark car exit the highway. The prosecutor said the camera was not recording motor vehicle traffic at the time of the shooting.

OTHER SUSPECTS -- The defense attorney wants criminal records for three people who were considered suspects, including the defendant's brother Cornelous Allen, but were ruled out early in the investigation. He also wants criminal records for the people whose identification cards were found on Scott. The prosecutor said his office need not relay information about people who have not been charged with crimes, adding that background checks involving the people whose identification cards were found on Scott didn't turn up any serious crimes.

JURY SELECTION -- The defense attorney is looking for information he could use to challenge the jury selection process because Magaña and co-counsel John R. Grele suspect that their client, a black man, will have a hard time finding 12 jurors who reflect the diversity of the community to sit in judgment. Allen's lawyers argue that they need more information than the court has provided. The prosecutor said his office does not have the materials requested.

Bee staff writer Susan Herendeen can be reached at sherendeen@modbee.com or 578-2338.