Prince George's County Council member Sue V. Mills and her husband won a last-minute zoning change from the council in 1985 for a small piece of undeveloped land they own in Oxon Hill -- a move that promptly increased the land's value by more than 500 percent.

The change, which allowed the property to be used for commercial development, was opposed by county planners and approved months after the county completed an extensive rezoning of the area that made no change in the Mills property.

The Mills zoning change was not illegal. But it is the latest in a series of land transactions by the Prince George's County government to come under public scrutiny and criticism. A county grand jury conducted a seven-month investigation of several county land purchases and in March issued a scathing report criticizing the county for conducting transactions that give an appearance of impropriety. The grand jury did not look into the Mills property.

Neighborhood activists say the rezoning of the property, which sits on a largely undeveloped tract along Bock Road, opened a critical wedge for development in an area where civic groups have fought commercial zoning for 20 years.

It also dramatically increased the property's value at a time when developers were scouring the area, attempting to assemble large parcels for commercial office buildings.

Sue Mills yesterday defended the zoning change, calling the property a "bad investment" handled by her husband, James E. Mills Jr. She said he sought the last-minute zoning change on land they have owned since 1967 so that he could build an office for his electrical contracting firm. She said he discovered soon after the change was made that the site was too small.

Neighbors of the Mills property in Oxon Hill say the zoning change was made without proper public input and discovered only after neighbors researched county property records. They say the vacant site is now an unsightly after-hours parking lot for industrial equipment.

"You can rest assured that if we had known they were trying to sneak this thing through, we would have been there at the county administration building screaming," said Joseph K. Burton, president of the Henson Valley Civic Association. Burton said the group has successfully fought most proposals for commercial development near the residential area.

During the weekend, Sue Mills sharply criticized two land transactions that the grand jury examined involving former Maryland secretary of state Fred C. Wineland, the father of council member F. Kirwan Wineland. She called them "dirty deals" and accused the county of committing "shameful acts" in its handling of them.

Mills said she had been unwittingly used by Fred Wineland to introduce zoning changes that escalated the values of his properties more than fourfold. Wineland has defended the purchases.

Mills said in an interview that she is unaware of the current use of the property she and her husband own and does not know the value of the land. In her official financial disclosure forms, she places the value at $60,000. County appraisers estimated the land's value in both 1987 and 1989 at $97,380.

A neighboring property of slightly smaller size, which does not have commercial zoning, was given an estimated worth of $17,700 in 1987. In the most recent assessment, it rose to $25,660.

Neighbors of the Mills site say they have been approached several times within the past year by developers hoping to assemble parcels for commercial development. Mills said she too has been approached but "the land is still sitting there."

In her own zoning case, Mills said the procedure the council used to approve the change by an 8 to 0 vote was "totally open and done in front of a roomful of people." Mills said she abstained from the vote and left the room so that there would be no conflict of interest.

County records show that on Jan. 24, 1985, James Mills filed a petition with the county requesting a change in the zoning on the 30,056-square-foot parcel, a narrow strip of land on Bock Road.

After extensive public hearings, the council had approved a zoning plan for the Oxon Hill area on July 24, 1984. Mills filed the petition on the last day of a six-month period when residents could protest zoning actions. He used a procedure usually reserved for exceptional cases.

Mills complained that the county had made a "mistake" by zoning the property for residential use and possible development as multifamily housing. He argued that the parcel was too small for multifamily housing. A county attorney, Joyce B. Hope, wrote in a May 15, 1985, opinion that Mills had shown sufficient cause for the council to reconsider the case.

Former council members James M. Herl and William Amonett and current council member Richard Castaldi introduced a resolution allowing the zoning change.

But at a public hearing attended by several county officials, county planner Craig Rovelstad recommended that the council turn down the request. He said commercial zoning was not suitable for the area, which was slated for possible condominium development. The council acted against his recommendation in a July 1985 vote.

County tax assessments show that the value of the Mills property increased from $14,960 in 1985 to $97,380 in 1987 after the zoning change went into effect.

In an earlier interview, Mills had been highly critical of Fred Wineland for obtaining her help on a zoning change, ostensibly so he could construct senior citizen housing. No housing was forthcoming, she said, and the zoning changes made the county pay higher prices when it bought the parcels.

The grand jury had looked into Wineland's sale of two abandoned Fort Washington drive-ins.

One parcel, which was sold for $1.1 million, was bought by the county for a commuter parking lot, despite the advice of an appraiser who suggested that the county purchase much cheaper acreage. Another parcel was bought from Wineland for $1.1 million by the Maryland National Capital Park and Planning Commission. But the county executive's office later traded the land for a plot of highway median property worth $300,000.