The father of a missing hiker last seen at the Grand Canyon National Park in Arizona says his son texted him telling him "he needed to be back with Mother Earth." 
 
 Drake Kramer, 21, of San Antonio, was last seen Sunday morning checking out of the Bright Angel Lodge, officials said. 
 
 His father, Robbin Kramer, said his son told him Monday that "he was at the Grand Canyon and he needed to be back with Mother Earth and set his soul free. At that point we really started getting worried and started calling and trying to get people to look for him." 
 
 The family reported Drake Kramer missing on Monday, and search efforts and a missing person investigation are now under way. 
 
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 "He posted on his Facebook when he was out here with his aunt last time: 'Wish I could stay.' And he had other posts about ... places he'd like to see, like the Redwood Forest, before he dies," Robbin Kramer said. 
 
 "We're focusing on the positive by trying to believe that him saying he needed to be with Mother Earth and set his soul free that he was talking about being out in nature and being one with nature," he said. 
 
 Drake Kramer loves to be outdoors and camp, his father said, but he's not sure if his son took appropriate hiking equipment with him. 
 
 "He was on the road to be a geologist so he could be out in nature where he loves to be," Robbin Kramer said. 
 
 Drake Kramer drove out west on I-10, according to his father. 
 
 "There had to be people that saw him when he filled up for gas. We'd really like to know if anyone saw him purchase any of the appropriate equipment with cash," Robbin Kramer said. "If anyone along the way saw him, heard anything, any information would be great." 
 
 Kirby-Lynn Shedlowski with the Grand Canyon National Park told ABC News, "We don't know what his plans were. He may be hiking, we just don't know." 
 
 "Nobody is sure where he is, what he's doing, if he's OK," Robbin Kramer said. "So many people that love him and are worried about him. Everyone is just on the edge of their seat." 
 
 Drake Kramer is described as having brown hair and blue eyes. He is 5 feet 7 inches tall and 140 pounds, officials say. Anyone with information can call the National Park Service Silent Witness Line at 928-638-7840. ||||| Drake Kramer missing for sixth day of searching 
 
 Photo: Courtesy Photo Image 1 of / 1 Caption Close Image 1 of 1 Drake L. Kramer, 21, of San Antonio, was reported missing from Grand Canyon National Park on Monday, Feb. 2, 2015. Drake L. Kramer, 21, of San Antonio, was reported missing from Grand Canyon National Park on Monday, Feb. 2, 2015. Photo: Courtesy Photo Drake Kramer missing for sixth day of searching 1 / 1 Back to Gallery 
 
 After six days of searching, a San Antonio man is still missing at the Grand Canyon National Park. 
 
 Drake L. Kramer, 21, was last seen Feb. 1 in the vicinity of the Bright Angel Lodge on the South Rim, the National Parks Service said in a press release. 
 
 Kramer stayed the previous night as a guest at the lodge, checking out the next morning. Family members reported him missing Monday. 
 
 No additional clues have been found in the time that the National Parks Service Search and Rescue has been searching for Kramer. 
 
 Because of this, the search will be scaled back to a continuous, but limited mode in which rangers and pilots search for clues when in the area, the release stated. 
 
 Kramer is described as 5’7, 140 pounds, brown hair and blue eyes. He is last known to be wearing blue jeans and an olive green sweatshirt. 
 
 For the past six days, park rangers have searched the South Rim developed area, stretching from Hermit’s Rest on the West Side to Grandview on the East, the release stated. 
 
 “Teams of searchers have walked miles along the canyon rim, searched heavily forested areas, utilized dog teams, performed several over the rim technical searches, and conducted multiple aerial reconnaissance missions to support ground searchers,” the release stated. 
 
 Posters with Kramer’s picture and description remain at various South Rim locations. Anyone with information regarding his whereabouts is encouraged to call the National Park Service Silent Witness Line at (928) 638-7840. 
 
 jbeltran@express-news.net 
 
 Twitter: @JBfromSA
– It's been a week since 21-year-old San Antonio native Drake Kramer was spotted at the Bright Angel Lodge on the South Rim of Grand Canyon National Park in Arizona. Last Monday, the avid hiker and aspiring geologist texted his father that he was at the Grand Canyon and "needed to be back with Mother Earth and set his soul free," his father tells ABC News; then he disappeared. "At that point we really started getting worried and started calling and trying to get people to look for him," his dad says. Kramer had visited the area with his aunt, and he posted "wish I could stay" on Facebook. "We're focusing on the positive by trying to believe that him saying he needed to be with Mother Earth and set his soul free that he was talking about being out in nature and being one with nature," says his dad. Because a week has gone by with no clues, efforts are now being scaled back to rangers and pilots looking for clues when they're in the area, reports San Antonio Express-News. Kramer is described as 5 feet 7 inches tall, 140 pounds, with blue eyes and brown hair. He was last seen in blue jeans and an olive-green sweatshirt. "We don't know what his plans were. He may be hiking, we just don't know," says a Grand Canyon National Park spokeswoman. (A group of 15 hikers was found in California's wilderness just last fall.)