SUE LAGARDE, Justice, Assigned.
Appellant Marty Wayne Stimson appeals his conviction for tampering with physical evidence. Appellant waived a jury and pleaded not guilty before the trial court. After hearing evidence, the trial court found appellant guilty. After hearing and considering punishment evidence, the trial court assessed punishment at ten years' imprisonment, probated for ten years. In his sole issue on appeal, appellant challenges the factual sufficiency of the evidence to support his conviction. We affirm the trial court's judgment. Facts Plano police officer Jennifer Chapman testified that on May 30, 2007, she was dispatched to appellant's residence in response to a call of "someone smoking narcotics." Chapman went to 1011 G Avenue Douglass Community Center. There she discovered appellant and a woman, later identified as Mary Walker, in an open shed. Walker had a pipe. In Chapman's opinion, the pipe had been used to smoke crack cocaine. Chapman did not, however, smell any smoke, the pipe was consistent with body temperature, and there was nothing consistent with burning narcotics. Walker was issued a citation for possession of drug paraphernalia. Chapman's back-up officer talked to appellant. Upon inquiry, it was discovered appellant had an outstanding municipal warrant for possession of alcohol. After appellant was arrested on the warrant, Chapman searched appellant and put him into a patrol car. Chapman did not search appellant's mouth at that time. Plano police officers Troy Bourgeois and Clinton Walker transported appellant to the police station. Bourgeois testified he transported appellant to the jail, where he searched appellant and found nothing. When Bourgeois asked appellant to open his mouth, appellant was "real evasive" about complying. Appellant moved his head around so Bourgeois could not see into appellant's mouth. Finally, appellant opened his mouth and Bourgeois succeeded in getting appellant to lift up his tongue. Bourgeois saw a white/yellowish rock about the size of a screw head underneath appellant's tongue. When Bourgeois asked appellant to open his mouth again, appellant had moved the object to the tip of his tongue. Before Bourgeois could say, "spit it out," appellant swallowed the object. Based on his training and experience, Bourgeois believed the object was crack cocaine. In his opinion, appellant was tampering with physical evidence in the jail. Although Bourgeois saw the object for only a split second, he said that, at that moment, an investigation ensued to determine what controlled substance was in appellant's mouth. The original search of appellant was conducted pursuant to his arrest under the warrant. However, Bourgeois was also searching appellant as part of book-in procedures to make sure no weapons or contraband went into the jail. Walker also testified he transported appellant to the jail on May 30, 2007. Walker observed Bourgeois having a hard time trying to see into appellant's mouth. Appellant offered no evidence at the guilt-innocence stage of trial. During the punishment hearing, appellant's prior convictions were admitted into evidence. Appellant testified he did not have crack cocaine in his mouth. He claimed he was taking medication prescribed by doctors from MHMR. Applicable Law In conducting a factual sufficiency review, an appellate court must review all of the evidence, both direct and circumstantial, in a neutral light to determine whether the fact-finder's verdict of guilt was rationally justified. See Watson v. State, 204 S.W.3d 404, 415 (Tex.Crim.App. 2006). Evidence that is legally sufficient to support a verdict may still be factually insufficient when the verdict seems clearly wrong or manifestly unjust, or it is against the great weight and preponderance of the evidence. See Marshall v. State, 210 S.W.3d 618, 625 (Tex.Crim.App. 2006), cert. denied, 128 S. Ct. 87 (2007). An appellate court must give due deference to the findings of the fact-finder, but the appellate court may substitute its judgment for the jury's credibility and weight determinations to a very limited degree. See id. A trial before the court is a unitary proceeding. See Barfield v. State, 63 S.W.3d 446, 451 (Tex.Crim.App. 2001). Therefore, in reviewing the sufficiency of the evidence to support the conviction, we consider the evidence presented during both the guilt/innocence and the punishment stages of the trial. See id. Under Texas law, tampering with physical evidence occurs when a person knowing that an investigation or official proceeding is pending or in progress alters, destroys, or conceals any record, document or thing with intent to impair its verity, legibility, or availability as evidence in the investigation or official proceeding. Tex. Penal Code Ann. § 37.09(a)(1) (Vernon Supp. 2007). Analysis Appellant contends the evidence was factually insufficient to support his conviction for tampering with physical evidence. Appellant argues that what happened at the jail was not during an ongoing investigation. Rather, it occurred during the administrative act of processing appellant into the jail. Appellant argues the only way he could have known an investigation was in progress was if Bourgeois had told him and, Bourgeois did not. Appellant further argues the event occurred either after the investigation at the scene of the arrest had terminated or before another investigation was initiated. And, without a pending or in-progress investigation, appellant argues, there was no tampering. The State argues Bourgeois was conducting an investigation to see what was in appellant's mouth. Bourgeois saw an object that, based on his training and experience, he believed was crack cocaine. Appellant swallowed the object before Bourgeois could tell him to spit it out. By swallowing the object, thereby concealing it, appellant impaired the investigation. It is undisputed the officers were originally dispatched to investigate suspected narcotics activity. During that investigation, an outstanding warrant for appellant was discovered. He was arrested pursuant to that warrant. Inherent in the book-in process following such arrest is an investigation to determine whether a suspect has contraband on his person. It was during this investigation the events giving rise to this charge occurred. Although there is no direct evidence Bourgeois told appellant he was being investigated for a criminal offense, it is a reasonable deduction from the evidence describing the events which occurred during the book-in process that appellant knew Bourgeois was "investigating" what was inside appellant's mouth. Not wanting Bourgeois to discover the object that was inside his mouth, appellant swallowed it, thereby impairing the investigation. As such, he was tampering with physical evidence. The judge, as fact-finder, was free to reject appellant's testimony that he was simply taking medication prescribed by MHMR doctors. Having reviewed the evidence under the appropriate standard, we conclude it is factually sufficient to show appellant altered, destroyed, or concealed an object believed to be crack cocaine and that he did so knowing that an investigation was in progress. We resolve appellant's sole issue against him. We affirm the trial court's judgment.