John Ferak

USA TODAY NETWORK-Wisconsin

Tension is building for "Making a Murderer" fans who are following the saga of convicted murderer Steven Avery, and April might be one of the most memorable months in the history of the case.

To recap:

Sheboygan County Judge Angela Sutkiewicz entered an order on Nov. 23, 2016, allowing for independent scientific testing on nine items of evidence related to the Oct. 31, 2005, murder of Teresa Halbach.

Last summer at the Manitowoc County courthouse, suburban Chicago attorney Kathleen Zellner told reporters that she would file her formal petition asking the judge to overturn Avery's conviction after the scientific testing was completed. That testing was scheduled to conclude in March.

On March 18, Zellner posted on Twitter: "To all the skeptics, doubters & haters just be patient because we are really going to make you mad."

On March 24, the "Making a Murderer" crews were back at the Avery Salvage Yard, filming for the second season, expected to be released later this year.

Those who are familiar with the case believe Zellner may file her much anticipated post-conviction motion in late April.

Now that the Avery case is heating up again, I returned to Avery Salvage Yard this past week. It was the first time I've been on the property in almost a year. I had permission to walk the grounds near Steven Avery's trailer, garage and backyard. I also canvassed the surrounding county roads and studied the adjacent quarries.

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I wanted to better acquaint myself with these key sites — several of which may hold special significance to Zellner's upcoming motion.

The burn pile pit: This was where Avery and his nephew Brendan Dassey were said to have incinerated Halbach's body on Halloween 2005.

My observations: This area, about 10 feet from the garage, is overgrown with weeds, lumpy rocks and uneven soil. The garage where Avery was said to have riddled Halbach's body with multiple rounds of ammunition still stands, but it's in shambles and looks like it would blow over with high winds. If trial testimony from prosecution witness Scott Tadych was credible, it's hard to believe the rickety wooden garage wasn't swept up in roaring flames. "They were almost as tall as the garage," testified Tadych, the boyfriend of Avery's sister. "Eight, 10 feet. It was a big fire."

Avery's trailer: A prime area of focus for Manitowoc County sheriff's deputies who investigated Halbach's disappearance.

My observations: You have to walk the property to grasp the closeness between Avery's trailer and the maze of nearby quarries that Avery's trial lawyers, Dean Strang and Jerry Buting, tried arguing was where Halbach was killed or dismembered. I took several photos near the edge of Avery's lot line. There's a nearly 10-foot berm that overlooks hundreds of acres of quarries. Moreover, Avery's backyard isn't that big and the yard is relatively flat. It's hard to see how authorities searching the red trailer, nearby garage and Avery's burn barrel on Nov. 5-7, 2005 managed to overlook the charred human bones that weren't discovered until about 1:45 p.m. on Nov. 8, 2005, the fourth day of the round-the-clock police presence at Avery's property. If somebody planted the charred human bones near Avery's burn pile pit, as Zellner contends occurred on Nov. 7, 2005, sneaking in through the back of the quarries would be pretty easy.

State 147: The highway in Manitowoc County that Halbach used to get to Avery Salvage during her many Auto Trader photography assignments.

My observations: Avery said Halbach left his property between 2 and 2:30 p.m., proceeding in her blue-green Toyota RAV4 back toward State 147. From Avery's yard, you can easily see the passing vehicles along 147. From Avery's, it's about 1½ miles to the intersection of 147 and County Q. It was the logical path for Halbach if she did, in fact, leave Avery's property.

Kuss Road: To reach Kuss Road, you would travel one mile south of State 147 along County Q. Kuss Road drew intense law enforcement activity over a six-hour period on Monday, Nov. 7, 2005, after a retired Manitowoc sheriff's official alerted others that he believed he found a shallow grave site along the road.

My observations: Kuss Road is only a half-mile long and it's seldom traveled. I spent 15 to 20 minutes here during a weekday afternoon and only saw one other motorist — a UPS delivery driver. Kuss Road is bordered by woodlands and consists of about eight houses. The road's dead end overlooks the quarries. However, at the Kuss Road cul-de-sac, there is a gravel access road for trucks needing to enter Joshua Radandt's quarries and this gravel road also leads into the Radandt deer camp property. The end of Kuss Road was also where several police dogs tracked Halbach's scent in the days prior to Avery's arrest. To walk from the cul-de-sac at Kuss Road to Avery's trailer would probably take about 10 minutes.

Quarry entrances: If you stay on County Q and drive another half-mile south of Kuss Road, you'll come upon the entrances for two connected quarries, Radandt's and the Manitowoc County-owned sand and gravel pit. Despite the focus on Avery's red trailer, several other Wisconsin law enforcement officials were looking for evidence and signs of dismemberment around these particular quarries. The most significant findings were the charred pelvic bones and some blood stains that contained a full DNA profile for an unknown male who was not Avery, lab reports showed. Although a state anthropologist believed the pelvic bones were human, special prosecutor Ken Kratz suggested they came from an animal.

My observations: If Zellner intends to show Halbach was killed somewhere other than Avery Salvage, law enforcement's recurring interest at Radandt's and the county-owned quarry land over the span of several days back in November 2005 may be a telling sign.

John Ferak of USA TODAY NETWORK-Wisconsin: 920-993-7115 or jferak@gannett.com; on Twitter @johnferak